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  <xs:element id="ardx_InvestmentsAndCashAmortizedCost" abstract="false" name="InvestmentsAndCashAmortizedCost" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_CashCashEquivalentsAndInvestmentsGrossUnrealizedGains" abstract="false" name="CashCashEquivalentsAndInvestmentsGrossUnrealizedGains" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_CashCashEquivalentsAndInvestmentsGrossUnrealizedLosses" abstract="false" name="CashCashEquivalentsAndInvestmentsGrossUnrealizedLosses" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_PrepaidCommercialManufacturing" abstract="false" name="PrepaidCommercialManufacturing" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ProductIBSRELAMember" abstract="true" name="ProductIBSRELAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_ProductXPHOZAHMember" abstract="true" name="ProductXPHOZAHMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ardx_GrossToNetSalesAccrualAndReserveClassificationAxis" abstract="true" name="GrossToNetSalesAccrualAndReserveClassificationAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
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  <xs:element id="ardx_ContractWithCustomerCopayAndReturnsMember" abstract="true" name="ContractWithCustomerCopayAndReturnsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="ardx_ContractWithCustomerGrossToNetSalesAccruals" abstract="false" name="ContractWithCustomerGrossToNetSalesAccruals" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_CencoraMember" abstract="true" name="CencoraMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="ardx_McKessonCorporationMember" abstract="true" name="McKessonCorporationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_KyowaKirinCo.LtdMember" abstract="true" name="KyowaKirinCo.LtdMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_LicenseAgreementDevelopmentCommercializationDistributionInJapanMember" abstract="true" name="LicenseAgreementDevelopmentCommercializationDistributionInJapanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_LicenseAgreementDevelopmentCommercializationDistributionInChinaMember" abstract="true" name="LicenseAgreementDevelopmentCommercializationDistributionInChinaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_LicenseAgreementDevelopmentCommercializationDistributionInCanadaMember" abstract="true" name="LicenseAgreementDevelopmentCommercializationDistributionInCanadaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_ShanghaiFosunPharmaceuticalIndustrialDevelopmentMember" abstract="true" name="ShanghaiFosunPharmaceuticalIndustrialDevelopmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_METiSTherapeuticsIncMember" abstract="true" name="METiSTherapeuticsIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="ardx_AstrazenecaMember" abstract="true" name="AstrazenecaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
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  <xs:element id="ardx_CollaborationAndLicensingAgreementsUpfrontLicenseFees" abstract="false" name="CollaborationAndLicensingAgreementsUpfrontLicenseFees" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_CollaborativeArrangementFeeReceivableForReductionInRoyaltyRate" abstract="false" name="CollaborativeArrangementFeeReceivableForReductionInRoyaltyRate" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_ContractWithCustomerLiabilityRevenueInvoicedAsPrepaymentsForProductSupplyCurrent" abstract="false" name="ContractWithCustomerLiabilityRevenueInvoicedAsPrepaymentsForProductSupplyCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityRevenueRecognizedCashNotReceivedCurrent" abstract="false" name="ContractWithCustomerLiabilityRevenueRecognizedCashNotReceivedCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityRevenueToBeRecognizedInNextTwelveMonths" abstract="false" name="ContractWithCustomerLiabilityRevenueToBeRecognizedInNextTwelveMonths" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ChangeInContractWithCustomerLiabilityNoncurrentRollforwardRollForward" abstract="true" name="ChangeInContractWithCustomerLiabilityNoncurrentRollforwardRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityRevenueInvoicedAsPrepaymentsForProductSupplyNoncurrent" abstract="false" name="ContractWithCustomerLiabilityRevenueInvoicedAsPrepaymentsForProductSupplyNoncurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityRevenueRecognizedCashNotReceivedNoncurrent" abstract="false" name="ContractWithCustomerLiabilityRevenueRecognizedCashNotReceivedNoncurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityDecreaseInRevenueToBeRecognizedInNextTwelveMonths" abstract="false" name="ContractWithCustomerLiabilityDecreaseInRevenueToBeRecognizedInNextTwelveMonths" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_ContractWithCustomerLiabilityTransactionCosts" abstract="false" name="ContractWithCustomerLiabilityTransactionCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ContractWithCustomerLiabilityAmortizationEffectiveInterestRatePercent" abstract="false" name="ContractWithCustomerLiabilityAmortizationEffectiveInterestRatePercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="ardx_DeferredRoyaltyObligationRollForward" abstract="true" name="DeferredRoyaltyObligationRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ardx_IncreaseDecreaseToDeferredRoyaltyObligationUpfrontPaymentNetOfTransactionCosts" abstract="false" name="IncreaseDecreaseToDeferredRoyaltyObligationUpfrontPaymentNetOfTransactionCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_IncreaseDecreaseToDeferredRoyaltyObligationRoyaltyApprovalMilestone" abstract="false" name="IncreaseDecreaseToDeferredRoyaltyObligationRoyaltyApprovalMilestone" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_IncreaseDecreaseToDeferredRoyaltyObligationNonCashInterestExpenseRelatedToSaleOfFutureRoyalties" abstract="false" name="IncreaseDecreaseToDeferredRoyaltyObligationNonCashInterestExpenseRelatedToSaleOfFutureRoyalties" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_IncreaseDecreaseToDeferredRoyaltyObligationRoyaltyDistributed" abstract="false" name="IncreaseDecreaseToDeferredRoyaltyObligationRoyaltyDistributed" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="ardx_SecuredOvernightFinancingRateSOFRFloorRateMember" abstract="true" name="SecuredOvernightFinancingRateSOFRFloorRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ardx_TermLoan2022Member" abstract="true" name="TermLoan2022Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
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  <xs:element id="ardx_DebtInstrumentClosingFeeAmount" abstract="false" name="DebtInstrumentClosingFeeAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_DebtInstrumentFeeDueUponMaturityAccelerationPrepaymentTerminationPercentage" abstract="false" name="DebtInstrumentFeeDueUponMaturityAccelerationPrepaymentTerminationPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
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  <xs:element id="ardx_LoanAgreementCovenantCashAndCashEquivalentsAsPercentageOfOutstandingLoanBalanceMinimum" abstract="false" name="LoanAgreementCovenantCashAndCashEquivalentsAsPercentageOfOutstandingLoanBalanceMinimum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="ardx_LoanAgreementCovenantCashAndCashEquivalentsAsPercentageOfOutstandingLoanBalanceCalculationPeriod" abstract="false" name="LoanAgreementCovenantCashAndCashEquivalentsAsPercentageOfOutstandingLoanBalanceCalculationPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="ardx_LoanAgreementCovenantNetProductRevenueAsPercentageOfOutstandingLoanBalanceMinimum" abstract="false" name="LoanAgreementCovenantNetProductRevenueAsPercentageOfOutstandingLoanBalanceMinimum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
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  <xs:element id="ardx_LoanAgreementExitFeeNetProductRevenueThresholdMetricTrailingSixMonthBasisMinimum" abstract="false" name="LoanAgreementExitFeeNetProductRevenueThresholdMetricTrailingSixMonthBasisMinimum" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_LesseeOperatingLeaseNumberOfRenewalOptions" abstract="false" name="LesseeOperatingLeaseNumberOfRenewalOptions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ardx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_OpenMarketSalesAgreement2021AtTheMarketOfferingMember" abstract="true" name="OpenMarketSalesAgreement2021AtTheMarketOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_OpenMarketSalesAgreement2023AtTheMarketOfferingMember" abstract="true" name="OpenMarketSalesAgreement2023AtTheMarketOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_MaximumAggregateOfferingPrice" abstract="false" name="MaximumAggregateOfferingPrice" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_EquitySalesAgreementProceedsFromSharesIssuedSinceInception" abstract="false" name="EquitySalesAgreementProceedsFromSharesIssuedSinceInception" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_SaleOfStockWeightedAveragePricePerShare" abstract="false" name="SaleOfStockWeightedAveragePricePerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:perShareItemType"/>
  <xs:element id="ardx_StockIssuanceCostCommissionPercent" abstract="false" name="StockIssuanceCostCommissionPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="ardx_TwoThousandFourteenEquityIncentiveAwardPlanMember" abstract="true" name="TwoThousandFourteenEquityIncentiveAwardPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_TwoThousandSixteenEmploymentCommencementIncentivePlanMember" abstract="true" name="TwoThousandSixteenEmploymentCommencementIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_EmployeeStockPurchasePlanMember" abstract="true" name="EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_IncreaseInSharesReservedForIssuanceMaximumSharesToBeIssuedUponInclusionOfForfeitedOrUnexercisedOptions" abstract="false" name="IncreaseInSharesReservedForIssuanceMaximumSharesToBeIssuedUponInclusionOfForfeitedOrUnexercisedOptions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ardx_IncreaseInSharesReservedForIssuanceOptionForAnnualIncreaseAsPercentageOfSharesOutstanding" abstract="false" name="IncreaseInSharesReservedForIssuanceOptionForAnnualIncreaseAsPercentageOfSharesOutstanding" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="ardx_CommonStockAdditionalCapitalSharesReservedForFutureIssuance" abstract="false" name="CommonStockAdditionalCapitalSharesReservedForFutureIssuance" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ardx_CommonStockSubjectToIssuedInducementGrantsShares" abstract="false" name="CommonStockSubjectToIssuedInducementGrantsShares" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ardx_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesUnderEmployeeStockPurchasePlan" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesUnderEmployeeStockPurchasePlan" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ardx_StockOptionsWeightedAverageRemainingContractualTermAbstract" abstract="true" name="StockOptionsWeightedAverageRemainingContractualTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ardx_StockOptionsAggregateIntrinsicValueAbstract" abstract="true" name="StockOptionsAggregateIntrinsicValueAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ardx_LaboratoryEquipmentMember" abstract="true" name="LaboratoryEquipmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_OfficeEquipmentAndFurnitureMember" abstract="true" name="OfficeEquipmentAndFurnitureMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_AccruedPaymentsDueToThirdParty" abstract="false" name="AccruedPaymentsDueToThirdParty" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_AccruedGrossToNetRevenueLiabilities" abstract="false" name="AccruedGrossToNetRevenueLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_AccruedSalesAndMarketingExpenses" abstract="false" name="AccruedSalesAndMarketingExpenses" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_EffectiveIncomeTaxRateReconciliationForeignWithholdingTaxPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationForeignWithholdingTaxPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="ardx_EffectiveIncomeTaxRateReconciliationTaxExpenseBenefitExecutiveCompensationDisallowedIRCSec162mPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationTaxExpenseBenefitExecutiveCompensationDisallowedIRCSec162mPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="ardx_DeferredTaxAssetsAmortizationAndDepreciation" abstract="false" name="DeferredTaxAssetsAmortizationAndDepreciation" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_DeferredTaxAssetsRoyaltyObligation" abstract="false" name="DeferredTaxAssetsRoyaltyObligation" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_DeferredTaxLiabilitiesRightOfUseAsset" abstract="false" name="DeferredTaxLiabilitiesRightOfUseAsset" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_IncomeTaxDisclosureTable" abstract="true" name="IncomeTaxDisclosureTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="ardx_TaxAuthorityStatesOtherThanCaliforniaMember" abstract="true" name="TaxAuthorityStatesOtherThanCaliforniaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_MinimumTaxCreditCarryforwardMember" abstract="true" name="MinimumTaxCreditCarryforwardMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_IncomeTaxDisclosureLineItems" abstract="true" name="IncomeTaxDisclosureLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ardx_OperatingLossCarryforwardsWithoutExpiration" abstract="false" name="OperatingLossCarryforwardsWithoutExpiration" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ardx_ResearchAndDevelopmentExpenseAdjusted" abstract="false" name="ResearchAndDevelopmentExpenseAdjusted" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_ShareBasedPaymentArrangementExpenseAdjusted" abstract="false" name="ShareBasedPaymentArrangementExpenseAdjusted" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_SegmentReportingOtherReconcilingItemAmount" abstract="false" name="SegmentReportingOtherReconcilingItemAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_AllocatedFacilitiesInformationTechnologyAndHumanResourcesCosts" abstract="false" name="AllocatedFacilitiesInformationTechnologyAndHumanResourcesCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ardx_PotentialCommonSharesAntiDilutiveEffectOnSecurities" abstract="false" name="PotentialCommonSharesAntiDilutiveEffectOnSecurities" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ardx_StrezsakVersusArdelyxIncMember" abstract="true" name="StrezsakVersusArdelyxIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_GoVersusRaabMember" abstract="true" name="GoVersusRaabMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ardx_YarboroughV.ArdelyxInc.Member" abstract="true" name="YarboroughV.ArdelyxInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ardx_ArdelyxInc.StockholderDerivativeLitigationMember" abstract="true" name="ArdelyxInc.StockholderDerivativeLitigationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ardx_RobertBlanksMember" abstract="true" name="RobertBlanksMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
