<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-01-21</periodOfReport>

    <issuer>
        <issuerCik>0001659323</issuerCik>
        <issuerName>Iterum Therapeutics plc</issuerName>
        <issuerTradingSymbol>ITRM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001553071</rptOwnerCik>
            <rptOwnerName>Frazier Healthcare VII, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 UNION STREET, SUITE 3200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SEATTLE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001575192</rptOwnerCik>
            <rptOwnerName>Frazier Healthcare VII-A, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 UNION STREET, SUITE 3200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SEATTLE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001654632</rptOwnerCik>
            <rptOwnerName>FHM VII, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 UNION STREET, SUITE 3200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SEATTLE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001654631</rptOwnerCik>
            <rptOwnerName>FHM VII, L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 UNION STREET, SUITE 3200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SEATTLE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>6.500% Exchangeable Senior Subordinated Note due 2025</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-01-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1167000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1167000.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-01-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1167000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1167000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>6.500% Exchangeable Senior Subordinated Note due 2025</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-01-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>333000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>333000.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-01-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>333000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>333000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On January 21, 2020, Iterum Therapeutics Bermuda Limited (the &quot;Issuer&quot;), a wholly-owned subsidiary of Iterum Therapeutics plc (the &quot;Company&quot;), issued and sold, among other things, 6.500% exchangeable senior subordinated notes due 2025 (the &quot;Exchangeable Notes&quot;) pursuant to a securities purchase agreement among the Issuer, the Company, the Company's wholly-owned subsidiaries and a group of accredited investors. Subject to the terms of the indenture governing the Exchangeable Notes, on or after January 21, 2021 until the second scheduled trading day immediately preceding January 15, 2025, holders may exchange the Exchangeable Notes at any time. The Exchangeable Notes are exchangeable into, at the Company's election, Ordinary Shares of the Company, cash or a combination of Ordinary Shares and cash, at an initial exchange rate of 1,000 shares per $1,000 principal amount of Exchangeable Notes (equivalent to an initial exchange price of approximately $1.00 per Ordinary Share).</footnote>
        <footnote id="F2">The Exchangeable Notes mature on January 31, 2025, unless earlier exchanged, redeemed or repurchased in accordance with their terms.</footnote>
        <footnote id="F3">The Exchangeable Note is held directly by Frazier Healthcare VII, L.P. (&quot;FH VII&quot;). The sole general partner of FH VII is FHM VII, L.P. and the general partner of FHM VII, L.P. is FHM VII, L.L.C., and each may be deemed to have sole voting, investment and dispositive power with respect to the securities held by FH VII. FHM VII, L.P. and FHM VII, L.L.C. disclaim Section 16 beneficial ownership of the securities held by FH VII, except to the extent of its pecuniary interest therein, if any.</footnote>
        <footnote id="F4">The Exchangeable Note is held directly by Frazier Healthcare VII-A, L.P. (&quot;FH VIIA&quot;). The sole general partner of FH VIIA is FHM VII, L.P. and the general partner of FHM VII, L.P. is FHM VII, L.L.C. FHM VII, L.P. and FHM VII, L.L.C. disclaim Section 16 beneficial ownership of the securities held by FH VIIA, except to the extent of its pecuniary interest therein, if any.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>__________________________________ Steve R. Bailey, Attorney-In-Fact for Frazier Healthcare VII, L.P.</signatureName>
        <signatureDate>2020-01-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Steve R. Bailey, Attorney-In-Fact for Frazier Healthcare VII-A, L.P.</signatureName>
        <signatureDate>2020-01-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Steve R. Bailey, Attorney-In-Fact for FHM VII, L.P.</signatureName>
        <signatureDate>2020-01-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Steve R. Bailey, Attorney-In-Fact for FHM VII, L.L.C.</signatureName>
        <signatureDate>2020-01-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
