<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019c96a9-f7f3-7430-b20a-c2fdafd5fcfc,g:477585a2-c071-4313-b5f3-3b43623e209b-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:bcrx="http://www.biocryst.com/20260331" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.biocryst.com/20260331">
  <xs:import namespace="http://fasb.org/srt/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd"/>
  <xs:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2025" schemaLocation="https://xbrl.sec.gov/country/2025/country-2025.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcrx-20260331_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcrx-20260331_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcrx-20260331_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcrx-20260331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://www.biocryst.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedBalanceSheets" roleURI="http://www.biocryst.com/role/CondensedConsolidatedBalanceSheets">
        <link:definition>9952151 - Statement - Condensed Consolidated Balance Sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedBalanceSheetsParenthetical" roleURI="http://www.biocryst.com/role/CondensedConsolidatedBalanceSheetsParenthetical">
        <link:definition>9952152 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofComprehensiveIncome" roleURI="http://www.biocryst.com/role/CondensedConsolidatedStatementsofComprehensiveIncome">
        <link:definition>9952153 - Statement - Condensed Consolidated Statements of Comprehensive Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofCashFlows" roleURI="http://www.biocryst.com/role/CondensedConsolidatedStatementsofCashFlows">
        <link:definition>9952154 - Statement - Condensed Consolidated Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofStockholdersDeficit" roleURI="http://www.biocryst.com/role/CondensedConsolidatedStatementsofStockholdersDeficit">
        <link:definition>9952155 - Statement - Condensed Consolidated Statements of Stockholders' Deficit</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SignificantAccountingPoliciesandConcentrationsofRisk" roleURI="http://www.biocryst.com/role/SignificantAccountingPoliciesandConcentrationsofRisk">
        <link:definition>9952156 - Disclosure - Significant Accounting Policies and Concentrations of Risk</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionofAstriaTherapeuticsInc" roleURI="http://www.biocryst.com/role/AcquisitionofAstriaTherapeuticsInc">
        <link:definition>9952157 - Disclosure - Acquisition of Astria Therapeutics, Inc.</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Revenue" roleURI="http://www.biocryst.com/role/Revenue">
        <link:definition>9952158 - Disclosure - Revenue</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestments" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestments">
        <link:definition>9952159 - Disclosure - Fair Value Measurements and Investments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TradeReceivables" roleURI="http://www.biocryst.com/role/TradeReceivables">
        <link:definition>9952160 - Disclosure - Trade Receivables</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Inventory" roleURI="http://www.biocryst.com/role/Inventory">
        <link:definition>9952161 - Disclosure - Inventory</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RoyaltyFinancingObligations" roleURI="http://www.biocryst.com/role/RoyaltyFinancingObligations">
        <link:definition>9952162 - Disclosure - Royalty Financing Obligations</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Debt" roleURI="http://www.biocryst.com/role/Debt">
        <link:definition>9952163 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligations" roleURI="http://www.biocryst.com/role/LeaseObligations">
        <link:definition>9952164 - Disclosure - Lease Obligations</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquity" roleURI="http://www.biocryst.com/role/StockholdersEquity">
        <link:definition>9952165 - Disclosure - Stockholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensation" roleURI="http://www.biocryst.com/role/StockbasedCompensation">
        <link:definition>9952166 - Disclosure - Stock-based Compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborativeandOtherRelationships" roleURI="http://www.biocryst.com/role/CollaborativeandOtherRelationships">
        <link:definition>9952167 - Disclosure - Collaborative and Other Relationships</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="WorkforceReduction" roleURI="http://www.biocryst.com/role/WorkforceReduction">
        <link:definition>9952168 - Disclosure - Workforce Reduction</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformation" roleURI="http://www.biocryst.com/role/SegmentInformation">
        <link:definition>9952169 - Disclosure - Segment Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingencies" roleURI="http://www.biocryst.com/role/CommitmentsandContingencies">
        <link:definition>9952170 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetLossIncomePerShare" roleURI="http://www.biocryst.com/role/NetLossIncomePerShare">
        <link:definition>9952171 - Disclosure - Net (Loss) Income Per Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SubsequentEvents" roleURI="http://www.biocryst.com/role/SubsequentEvents">
        <link:definition>9952172 - Disclosure - Subsequent Events</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SignificantAccountingPoliciesandConcentrationsofRiskPolicies" roleURI="http://www.biocryst.com/role/SignificantAccountingPoliciesandConcentrationsofRiskPolicies">
        <link:definition>9955511 - Disclosure - Significant Accounting Policies and Concentrations of Risk (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SignificantAccountingPoliciesandConcentrationsofRiskTables" roleURI="http://www.biocryst.com/role/SignificantAccountingPoliciesandConcentrationsofRiskTables">
        <link:definition>9955512 - Disclosure - Significant Accounting Policies and Concentrations of Risk (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionofAstriaTherapeuticsIncTables" roleURI="http://www.biocryst.com/role/AcquisitionofAstriaTherapeuticsIncTables">
        <link:definition>9955513 - Disclosure - Acquisition of Astria Therapeutics, Inc. (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenueTables" roleURI="http://www.biocryst.com/role/RevenueTables">
        <link:definition>9955514 - Disclosure - Revenue (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestmentsTables" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestmentsTables">
        <link:definition>9955515 - Disclosure - Fair Value Measurements and Investments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TradeReceivablesTables" roleURI="http://www.biocryst.com/role/TradeReceivablesTables">
        <link:definition>9955516 - Disclosure - Trade Receivables (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryTables" roleURI="http://www.biocryst.com/role/InventoryTables">
        <link:definition>9955517 - Disclosure - Inventory (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RoyaltyFinancingObligationsTables" roleURI="http://www.biocryst.com/role/RoyaltyFinancingObligationsTables">
        <link:definition>9955518 - Disclosure - Royalty Financing Obligations (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsTables" roleURI="http://www.biocryst.com/role/LeaseObligationsTables">
        <link:definition>9955519 - Disclosure - Lease Obligations (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityTables" roleURI="http://www.biocryst.com/role/StockholdersEquityTables">
        <link:definition>9955520 - Disclosure - Stockholders' Equity (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationTables" roleURI="http://www.biocryst.com/role/StockbasedCompensationTables">
        <link:definition>9955521 - Disclosure - Stock-based Compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="WorkforceReductionTables" roleURI="http://www.biocryst.com/role/WorkforceReductionTables">
        <link:definition>9955522 - Disclosure - Workforce Reduction (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationTables" roleURI="http://www.biocryst.com/role/SegmentInformationTables">
        <link:definition>9955523 - Disclosure - Segment Information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetLossIncomePerShareTables" roleURI="http://www.biocryst.com/role/NetLossIncomePerShareTables">
        <link:definition>9955524 - Disclosure - Net (Loss) Income Per Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SignificantAccountingPoliciesandConcentrationsofRiskDetails" roleURI="http://www.biocryst.com/role/SignificantAccountingPoliciesandConcentrationsofRiskDetails">
        <link:definition>9955525 - Disclosure - Significant Accounting Policies and Concentrations of Risk (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SignificantAccountingPoliciesandConcentrationsofRiskScheduleofRevenuesDetails" roleURI="http://www.biocryst.com/role/SignificantAccountingPoliciesandConcentrationsofRiskScheduleofRevenuesDetails">
        <link:definition>9955526 - Disclosure - Significant Accounting Policies and Concentrations of Risk - Schedule of Revenues (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionofAstriaTherapeuticsIncNarrativeDetails" roleURI="http://www.biocryst.com/role/AcquisitionofAstriaTherapeuticsIncNarrativeDetails">
        <link:definition>9955527 - Disclosure - Acquisition of Astria Therapeutics, Inc. - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionofAstriaTherapeuticsIncConsiderationTransferredDetails" roleURI="http://www.biocryst.com/role/AcquisitionofAstriaTherapeuticsIncConsiderationTransferredDetails">
        <link:definition>9955528 - Disclosure - Acquisition of Astria Therapeutics, Inc. - Consideration Transferred (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionofAstriaTherapeuticsIncSeparationCostsDetails" roleURI="http://www.biocryst.com/role/AcquisitionofAstriaTherapeuticsIncSeparationCostsDetails">
        <link:definition>9955529 - Disclosure - Acquisition of Astria Therapeutics, Inc. - Separation Costs (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenueScheduleofRevenuesDetails" roleURI="http://www.biocryst.com/role/RevenueScheduleofRevenuesDetails">
        <link:definition>9955530 - Disclosure - Revenue - Schedule of Revenues (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenueNarrativeDetails" roleURI="http://www.biocryst.com/role/RevenueNarrativeDetails">
        <link:definition>9955531 - Disclosure - Revenue - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestmentsScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestmentsScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails">
        <link:definition>9955532 - Disclosure - Fair Value Measurements and Investments - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestmentsScheduleofFairValueoftheCompanysInvestmentsbyTypeDetails" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestmentsScheduleofFairValueoftheCompanysInvestmentsbyTypeDetails">
        <link:definition>9955533 - Disclosure - Fair Value Measurements and Investments - Schedule of Fair Value of the Company's Investments by Type (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestmentsNarrativeDetails" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestmentsNarrativeDetails">
        <link:definition>9955534 - Disclosure - Fair Value Measurements and Investments - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandInvestmentsScheduleofMaturityofInvestmentsDetails" roleURI="http://www.biocryst.com/role/FairValueMeasurementsandInvestmentsScheduleofMaturityofInvestmentsDetails">
        <link:definition>9955535 - Disclosure - Fair Value Measurements and Investments - Schedule of Maturity of Investments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TradeReceivablesDetails" roleURI="http://www.biocryst.com/role/TradeReceivablesDetails">
        <link:definition>9955536 - Disclosure - Trade Receivables (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryDetails" roleURI="http://www.biocryst.com/role/InventoryDetails">
        <link:definition>9955537 - Disclosure - Inventory (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RoyaltyFinancingObligationsNarrativeDetails" roleURI="http://www.biocryst.com/role/RoyaltyFinancingObligationsNarrativeDetails">
        <link:definition>9955538 - Disclosure - Royalty Financing Obligations - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RoyaltyFinancingObligationsScheduleofRoyaltyFinancingObligationsDetails" roleURI="http://www.biocryst.com/role/RoyaltyFinancingObligationsScheduleofRoyaltyFinancingObligationsDetails">
        <link:definition>9955539 - Disclosure - Royalty Financing Obligations - Schedule of Royalty Financing Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtDetails" roleURI="http://www.biocryst.com/role/DebtDetails">
        <link:definition>9955540 - Disclosure - Debt (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsNarrativeDetails" roleURI="http://www.biocryst.com/role/LeaseObligationsNarrativeDetails">
        <link:definition>9955541 - Disclosure - Lease Obligations - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsScheduleofAggregateLeaseExpenseUnderOperatingLeasesDetails" roleURI="http://www.biocryst.com/role/LeaseObligationsScheduleofAggregateLeaseExpenseUnderOperatingLeasesDetails">
        <link:definition>9955542 - Disclosure - Lease Obligations - Schedule of Aggregate Lease Expense Under Operating Leases (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsScheduleofOtherSupplementalInformationRelatedtoLeasesDetails" roleURI="http://www.biocryst.com/role/LeaseObligationsScheduleofOtherSupplementalInformationRelatedtoLeasesDetails">
        <link:definition>9955543 - Disclosure - Lease Obligations - Schedule of Other Supplemental Information Related to Leases (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsScheduleofMaturitiesofLeaseLiabilitiesDetails" roleURI="http://www.biocryst.com/role/LeaseObligationsScheduleofMaturitiesofLeaseLiabilitiesDetails">
        <link:definition>9955544 - Disclosure - Lease Obligations - Schedule of Maturities of Lease Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsScheduleofMaturitiesofLeaseLiabilitiesDetails_1" roleURI="http://www.biocryst.com/role/LeaseObligationsScheduleofMaturitiesofLeaseLiabilitiesDetails_1">
        <link:definition>9955544 - Disclosure - Lease Obligations - Schedule of Maturities of Lease Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeaseObligationsScheduleofSupplementalCashFlowsDetails" roleURI="http://www.biocryst.com/role/LeaseObligationsScheduleofSupplementalCashFlowsDetails">
        <link:definition>9955545 - Disclosure - Lease Obligations - Schedule of Supplemental Cash Flows (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityNarrativeDetails" roleURI="http://www.biocryst.com/role/StockholdersEquityNarrativeDetails">
        <link:definition>9955546 - Disclosure - Stockholders' Equity - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityScheduleofSharesReservedforFutureIssuanceDetails" roleURI="http://www.biocryst.com/role/StockholdersEquityScheduleofSharesReservedforFutureIssuanceDetails">
        <link:definition>9955547 - Disclosure - Stockholders' Equity - Schedule of Shares Reserved for Future Issuance (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationNarrativeDetails" roleURI="http://www.biocryst.com/role/StockbasedCompensationNarrativeDetails">
        <link:definition>9955548 - Disclosure - Stock-based Compensation - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationScheduleofShareBasedCompensationDetails" roleURI="http://www.biocryst.com/role/StockbasedCompensationScheduleofShareBasedCompensationDetails">
        <link:definition>9955549 - Disclosure - Stock-based Compensation - Schedule of Share-Based Compensation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationScheduleofReconciliationRecurringBasisFairValueMeasurementsDetails" roleURI="http://www.biocryst.com/role/StockbasedCompensationScheduleofReconciliationRecurringBasisFairValueMeasurementsDetails">
        <link:definition>9955550 - Disclosure - Stock-based Compensation - Schedule of Reconciliation Recurring Basis Fair Value Measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationScheduleofOptionActivityDetails" roleURI="http://www.biocryst.com/role/StockbasedCompensationScheduleofOptionActivityDetails">
        <link:definition>9955551 - Disclosure - Stock-based Compensation - Schedule of Option Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedCompensationScheduleofRestrictedStockUnitActivityDetails" roleURI="http://www.biocryst.com/role/StockbasedCompensationScheduleofRestrictedStockUnitActivityDetails">
        <link:definition>9955552 - Disclosure - Stock-based Compensation - Schedule of Restricted Stock Unit Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CollaborativeandOtherRelationshipsDetails" roleURI="http://www.biocryst.com/role/CollaborativeandOtherRelationshipsDetails">
        <link:definition>9955553 - Disclosure - Collaborative and Other Relationships (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="WorkforceReductionNarrativeDetails" roleURI="http://www.biocryst.com/role/WorkforceReductionNarrativeDetails">
        <link:definition>9955554 - Disclosure - Workforce Reduction - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="WorkforceReductionScheduleofAccruedLiabilityActivityDetails" roleURI="http://www.biocryst.com/role/WorkforceReductionScheduleofAccruedLiabilityActivityDetails">
        <link:definition>9955555 - Disclosure - Workforce Reduction - Schedule of Accrued Liability Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationNarrativeDetails" roleURI="http://www.biocryst.com/role/SegmentInformationNarrativeDetails">
        <link:definition>9955556 - Disclosure - Segment Information - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationScheduleofSegmentReportingInformationbySegmentDetails" roleURI="http://www.biocryst.com/role/SegmentInformationScheduleofSegmentReportingInformationbySegmentDetails">
        <link:definition>9955557 - Disclosure - Segment Information - Schedule of Segment Reporting Information, by Segment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetLossIncomePerShareScheduleofEarningsPerShareDetails" roleURI="http://www.biocryst.com/role/NetLossIncomePerShareScheduleofEarningsPerShareDetails">
        <link:definition>9955558 - Disclosure - Net (Loss) Income Per Share - Schedule of Earnings Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetLossIncomePerShareScheduleofPotentialSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails" roleURI="http://www.biocryst.com/role/NetLossIncomePerShareScheduleofPotentialSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails">
        <link:definition>9955559 - Disclosure - Net (Loss) Income Per Share - Schedule of Potential Shares Excluded from Computation of Diluted Net Income (Loss) Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SubsequentEventDetails" roleURI="http://www.biocryst.com/role/SubsequentEventDetails">
        <link:definition>9955560 - Disclosure - Subsequent Event (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="bcrx_RightOfUseAssetsNoncurrent" abstract="false" name="RightOfUseAssetsNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ShareBasedLiability" abstract="false" name="ShareBasedLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesCurrent" abstract="false" name="RoyaltyFinancingLiabilitiesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesNoncurrent" abstract="false" name="RoyaltyFinancingLiabilitiesNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_LicenseAndOtherRevenuesMember" abstract="true" name="LicenseAndOtherRevenuesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AcquiredInProcessResearchAndDevelopment" abstract="false" name="AcquiredInProcessResearchAndDevelopment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_FairValueAdjustmentShareBasedLiability" abstract="false" name="FairValueAdjustmentShareBasedLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_NonCashInterestExpenseOnRoyaltyFinancingLiabilities" abstract="false" name="NonCashInterestExpenseOnRoyaltyFinancingLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AmortizationOfDebtIssuanceCostsOnTermLoans" abstract="false" name="AmortizationOfDebtIssuanceCostsOnTermLoans" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AmortizationOfPremiumDiscountOnInvestments" abstract="false" name="AmortizationOfPremiumDiscountOnInvestments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_IncreaseDecreaseInRoyaltyFinancingLiabilities" abstract="false" name="IncreaseDecreaseInRoyaltyFinancingLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ProceedsFromStockIssuedInPlaceOfCashRetainer" abstract="false" name="ProceedsFromStockIssuedInPlaceOfCashRetainer" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RepaymentOfRoyaltyFinancingLiabilitiesPrincipal" abstract="false" name="RepaymentOfRoyaltyFinancingLiabilitiesPrincipal" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RestrictedCashAndCashEquivalentsIncludedInOtherAssetsNonCurrent" abstract="false" name="RestrictedCashAndCashEquivalentsIncludedInOtherAssetsNonCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_WithholdingTaxesAccrued" abstract="false" name="WithholdingTaxesAccrued" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AdjustmentsToAdditionalPaidInCapitalRemeasurementOfShareBasedLiability" abstract="false" name="AdjustmentsToAdditionalPaidInCapitalRemeasurementOfShareBasedLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_SettlementOfShareBasedLiability" abstract="false" name="SettlementOfShareBasedLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_FairValueDisclosuresAndInvestmentsTextBlock" abstract="false" name="FairValueDisclosuresAndInvestmentsTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_TradeReceivablesTextBlock" abstract="false" name="TradeReceivablesTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesTextBlock" abstract="false" name="RoyaltyFinancingLiabilitiesTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_DescriptionOfCompanyPolicyTextBlock" abstract="false" name="DescriptionOfCompanyPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_AccruedExpensesPolicyTextBlock" abstract="false" name="AccruedExpensesPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_InterestExpenseDeferredFinancingCostsAndRoyaltyFinancingLiabilitiesPolicyTextBlock" abstract="false" name="InterestExpenseDeferredFinancingCostsAndRoyaltyFinancingLiabilitiesPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_ConcentrationOfMarketRiskPolicyTextBlock" abstract="false" name="ConcentrationOfMarketRiskPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilitiesTableTextBlock" abstract="false" name="RoyaltyFinancingLiabilitiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_OtherSupplementalInformationRelatedToLeasesTableTextBlock" abstract="false" name="OtherSupplementalInformationRelatedToLeasesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="bcrx_SignificantAccountingPoliciesAndConcentrationsOfRiskTable" abstract="true" name="SignificantAccountingPoliciesAndConcentrationsOfRiskTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_CollateralForCreditMember" abstract="true" name="CollateralForCreditMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_LaboratoryEquipmentOfficeEquipmentAndSoftwareMember" abstract="true" name="LaboratoryEquipmentOfficeEquipmentAndSoftwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ORLADEYOMember" abstract="true" name="ORLADEYOMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_SignificantAccountingPoliciesAndConcentrationsOfRiskLineItems" abstract="true" name="SignificantAccountingPoliciesAndConcentrationsOfRiskLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_MaturityPeriodOfHighQualityMarketableSecurities" abstract="false" name="MaturityPeriodOfHighQualityMarketableSecurities" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="bcrx_AverageMaturityPeriodOfHighQualityMarketableSecurities" abstract="false" name="AverageMaturityPeriodOfHighQualityMarketableSecurities" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="bcrx_MaturityPeriodOfShortTermInvestment" abstract="false" name="MaturityPeriodOfShortTermInvestment" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="bcrx_LongTermInvestmentMaturityMinimum" abstract="false" name="LongTermInvestmentMaturityMinimum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="bcrx_CollaborativeAndOtherResearchAndDevelopmentMember" abstract="true" name="CollaborativeAndOtherResearchAndDevelopmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AstriaMember" abstract="true" name="AstriaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AssetAcquisitionCommonStockConversionRatio" abstract="false" name="AssetAcquisitionCommonStockConversionRatio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="bcrx_AssetAcquisitionCashConversionRatio" abstract="false" name="AssetAcquisitionCashConversionRatio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="bcrx_DirectTransactionCosts" abstract="false" name="DirectTransactionCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionStatedStockPricePayoutOfAcquireeStockOptions" abstract="false" name="AssetAcquisitionStatedStockPricePayoutOfAcquireeStockOptions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="bcrx_AssetAcquisitionPayoutOfAcquireeStockOptionsAmount" abstract="false" name="AssetAcquisitionPayoutOfAcquireeStockOptionsAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionPayoutOfAcquireeStockOptionsPreCombinationServiceAmount" abstract="false" name="AssetAcquisitionPayoutOfAcquireeStockOptionsPreCombinationServiceAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionPayoutOfAcquireeStockOptionsPostCombinationServiceAmount" abstract="false" name="AssetAcquisitionPayoutOfAcquireeStockOptionsPostCombinationServiceAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionConsiderationTransferredDirectTransactionCosts" abstract="false" name="AssetAcquisitionConsiderationTransferredDirectTransactionCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionCashAndCashEquivalent" abstract="false" name="AssetAcquisitionCashAndCashEquivalent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionShortTermInvestments" abstract="false" name="AssetAcquisitionShortTermInvestments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionTradeReceivables" abstract="false" name="AssetAcquisitionTradeReceivables" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionPrepaidExpenseAndOtherAssetCurrent" abstract="false" name="AssetAcquisitionPrepaidExpenseAndOtherAssetCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionOtherAssets" abstract="false" name="AssetAcquisitionOtherAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionLeasesRightOfUseAsset" abstract="false" name="AssetAcquisitionLeasesRightOfUseAsset" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionAccountsPayable" abstract="false" name="AssetAcquisitionAccountsPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionAccruedLiabilitiesCurrent" abstract="false" name="AssetAcquisitionAccruedLiabilitiesCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionOperatingLeaseLiabilityCurrent" abstract="false" name="AssetAcquisitionOperatingLeaseLiabilityCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionDeferredRevenueCurrent" abstract="false" name="AssetAcquisitionDeferredRevenueCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionOperatingLeaseLiabilityNoncurrent" abstract="false" name="AssetAcquisitionOperatingLeaseLiabilityNoncurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionDeferredRevenueNoncurrent" abstract="false" name="AssetAcquisitionDeferredRevenueNoncurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet" abstract="false" name="AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AssetAcquisitionConsiderationTransferredEquityInterestSharesIssued" abstract="false" name="AssetAcquisitionConsiderationTransferredEquityInterestSharesIssued" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="bcrx_AssetAcquisitionPricePerShare" abstract="false" name="AssetAcquisitionPricePerShare" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="bcrx_OtherIncomeFromContractWithCustomerMember" abstract="true" name="OtherIncomeFromContractWithCustomerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterOneYearAndBeforeTwoYears" abstract="false" name="DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterOneYearAndBeforeTwoYears" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_PeramivirMember" abstract="true" name="PeramivirMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_InventoryIncludingNoncurrentPortion" abstract="false" name="InventoryIncludingNoncurrentPortion" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltiesMonetizationsTable" abstract="true" name="RoyaltiesMonetizationsTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_RPI2019IntermediateFinanceTrustMember" abstract="true" name="RPI2019IntermediateFinanceTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RPI2021And2020IntermediateFinanceTrustMember" abstract="true" name="RPI2021And2020IntermediateFinanceTrustMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_OMERSCapitalMarketsMember" abstract="true" name="OMERSCapitalMarketsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_The2021RPIRoyaltyPurchaseAgreementMember" abstract="true" name="The2021RPIRoyaltyPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_BioCrystIrelandMember" abstract="true" name="BioCrystIrelandMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_FutureRoyaltiesPayableMember" abstract="true" name="FutureRoyaltiesPayableMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesRangeAxis" abstract="true" name="AnnualNetSalesRangeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_AnnualNetSalesRangeDomain" abstract="true" name="AnnualNetSalesRangeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesUnder350000Member" abstract="true" name="AnnualNetSalesUnder350000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesBetween350000And550000Member" abstract="true" name="AnnualNetSalesBetween350000And550000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesOver550000Member" abstract="true" name="AnnualNetSalesOver550000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesUnder150000Member" abstract="true" name="AnnualNetSalesUnder150000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesBetween150000And230000Member" abstract="true" name="AnnualNetSalesBetween150000And230000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AnnualNetSalesOver230000Member" abstract="true" name="AnnualNetSalesOver230000Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RoyaltiesMonetizationsLineItems" abstract="true" name="RoyaltiesMonetizationsLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInKeyTerritories" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInKeyTerritories" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfSublicenseRevenueInOtherMarkets" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfSublicenseRevenueInOtherMarkets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInOtherMarkets" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesInOtherMarkets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPurchasePriceAmount" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPurchasePriceAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_SharesIssuedCommonStockPremium" abstract="false" name="SharesIssuedCommonStockPremium" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSales" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSales" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesBasedOnReductionInSales" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfAnnualNetSalesBasedOnReductionInSales" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPercentageOfPurchasePrice" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPercentageOfPurchasePrice" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_RoyaltyPurchaseAgreementRoyaltiesPaidAndPayable" abstract="false" name="RoyaltyPurchaseAgreementRoyaltiesPaidAndPayable" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_DisposalGroupIncludingDiscontinuedOperationConsiderationRoyaltyReleaseFee" abstract="false" name="DisposalGroupIncludingDiscontinuedOperationConsiderationRoyaltyReleaseFee" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_InterestPaidRoyaltyFinancingLiabilities" abstract="false" name="InterestPaidRoyaltyFinancingLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_TwentyTwentyRPIRoyaltyAgreementMember" abstract="true" name="TwentyTwentyRPIRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_TwentyTwentyOneRPIRoyaltyAgreementMember" abstract="true" name="TwentyTwentyOneRPIRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_OMERSRoyaltyAgreementMember" abstract="true" name="OMERSRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RoyaltyMonetizationsLineItems" abstract="true" name="RoyaltyMonetizationsLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_RoyaltyMontizationsRollForward" abstract="true" name="RoyaltyMontizationsRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_RoyaltyFinancingLiabilities" abstract="false" name="RoyaltyFinancingLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RoyaltyRevenuesPaidAndPayable" abstract="false" name="RoyaltyRevenuesPaidAndPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_BlackstoneMember" abstract="true" name="BlackstoneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_PharmakonAdvisorsLPMember" abstract="true" name="PharmakonAdvisorsLPMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AthyriumMember" abstract="true" name="AthyriumMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_DebtCovenantTermsAxis" abstract="true" name="DebtCovenantTermsAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="bcrx_DebtCovenantTermsDomain" abstract="true" name="DebtCovenantTermsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_PikInterestPaymentIsMadeMember" abstract="true" name="PikInterestPaymentIsMadeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_BlackstoneLoanAgreementMember" abstract="true" name="BlackstoneLoanAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_LoanAgreementMember" abstract="true" name="LoanAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_TermLoanTrancheAMember" abstract="true" name="TermLoanTrancheAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_SeniorCreditFacilityMember" abstract="true" name="SeniorCreditFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_DebtInstrumentVariableRateFloor" abstract="false" name="DebtInstrumentVariableRateFloor" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="bcrx_DebtInstrumentPortionOfInterestThatMayBeCapitalizedAsPrincipal" abstract="false" name="DebtInstrumentPortionOfInterestThatMayBeCapitalizedAsPrincipal" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_DebtInstrumentVoluntaryPrepaymentAggregatePrincipalAmount" abstract="false" name="DebtInstrumentVoluntaryPrepaymentAggregatePrincipalAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_DebtInstrumentVoluntaryPrepaymentWholeMultipleOfMinimumPrepayment" abstract="false" name="DebtInstrumentVoluntaryPrepaymentWholeMultipleOfMinimumPrepayment" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_DebtInstrumentCapitalizedInterestRate" abstract="false" name="DebtInstrumentCapitalizedInterestRate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="bcrx_DebtInstrumentNumberOfPrepayments" abstract="false" name="DebtInstrumentNumberOfPrepayments" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_FinancingLeaseExpense" abstract="false" name="FinancingLeaseExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_FinanceLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="FinanceLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_SaleOfStockSharesMaximumOffering" abstract="false" name="SaleOfStockSharesMaximumOffering" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="bcrx_IncentivePlanMember" abstract="true" name="IncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_InducementPlanMember" abstract="true" name="InducementPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_EmployeeStockPurchasePlanMember" abstract="true" name="EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_IncentivePlanAndInducementPlanMember" abstract="true" name="IncentivePlanAndInducementPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ShareBasedPaymentArrangementNumberOfPlans" abstract="false" name="ShareBasedPaymentArrangementNumberOfPlans" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_GainLossOnRemeasurementOfShareBasedLiability" abstract="false" name="GainLossOnRemeasurementOfShareBasedLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisRemeasurementOfShareBasedLiability" abstract="false" name="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisRemeasurementOfShareBasedLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationOptionsExercised" abstract="false" name="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationOptionsExercised" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_AstriaTherapeuticsInc.Member" abstract="true" name="AstriaTherapeuticsInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_KakenLicenseAgreementMember" abstract="true" name="KakenLicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ResearchAndDevelopmentServicesMember" abstract="true" name="ResearchAndDevelopmentServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_LicenseAgreementUpfrontPayment" abstract="false" name="LicenseAgreementUpfrontPayment" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_LicenseAgreementPotentialFutureConsideration" abstract="false" name="LicenseAgreementPotentialFutureConsideration" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_RevenueRemainingPerformanceObligationVariableConsiderationRoyaltyPercentage" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationRoyaltyPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="bcrx_NumberOfPerformanceObligations" abstract="false" name="NumberOfPerformanceObligations" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="bcrx_ContractWithCustomerTransactionPrice" abstract="false" name="ContractWithCustomerTransactionPrice" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ContractWithCustomerTransactionPriceFixedConsideration" abstract="false" name="ContractWithCustomerTransactionPriceFixedConsideration" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ContractWithCustomerTransactionPriceVariableConsideration" abstract="false" name="ContractWithCustomerTransactionPriceVariableConsideration" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_CashCashEquivalentsShortAndLongTermInvestments" abstract="false" name="CashCashEquivalentsShortAndLongTermInvestments" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_NavenibartMember" abstract="true" name="NavenibartMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_BCX17725Member" abstract="true" name="BCX17725Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_BerotralstatMember" abstract="true" name="BerotralstatMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_AvoralstatMember" abstract="true" name="AvoralstatMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_STAR0310Member" abstract="true" name="STAR0310Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ResearchDiscoveryAndPreclinicalProgramsMember" abstract="true" name="ResearchDiscoveryAndPreclinicalProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_CompensationAndRelatedPersonnelCostsMember" abstract="true" name="CompensationAndRelatedPersonnelCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_OtherExpenses1Member" abstract="true" name="OtherExpenses1Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_ResearchAndDevelopmentExpenseAcquiredInProcessCost" abstract="false" name="ResearchAndDevelopmentExpenseAcquiredInProcessCost" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="bcrx_IncrementalCommonSharesAttributableToDilutiveEffectOfSharePurchasePlans" abstract="false" name="IncrementalCommonSharesAttributableToDilutiveEffectOfSharePurchasePlans" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="bcrx_LicenseAgreementMember" abstract="true" name="LicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_NeopharmedIrishAffiliateMember" abstract="true" name="NeopharmedIrishAffiliateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_RonDullingerMember" abstract="true" name="RonDullingerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_JonStonehouseMember" abstract="true" name="JonStonehouseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_CommonStockUnderlyingStockOptionsMember" abstract="true" name="CommonStockUnderlyingStockOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="bcrx_CommonStockUnderlyingRestrictedStockUnitsMember" abstract="true" name="CommonStockUnderlyingRestrictedStockUnitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
