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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-11-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001604950</issuerCik>
        <issuerName>scPharmaceuticals Inc.</issuerName>
        <issuerTradingSymbol>SCPH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001197089</rptOwnerCik>
            <rptOwnerName>SUN PHARMACEUTICAL INDUSTRIES LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUN HOUSE, 201 B/1, WESTERN EXPRESS</rptOwnerStreet1>
            <rptOwnerStreet2>HIGHWAY, GOREGAON (E)</rptOwnerStreet2>
            <rptOwnerCity>MUMBAI MAHARASHTRA</rptOwnerCity>
            <rptOwnerState>K7</rptOwnerState>
            <rptOwnerZipCode>400063</rptOwnerZipCode>
            <rptOwnerStateDescription>INDIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001249644</rptOwnerCik>
            <rptOwnerName>SHANGHVI DILIP S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUN HOUSE, 201 B/1, WESTERN EXPRESS</rptOwnerStreet1>
            <rptOwnerStreet2>HIGHWAY, GOREGAON (E)</rptOwnerStreet2>
            <rptOwnerCity>MUMBAI MAHARASHTRA</rptOwnerCity>
            <rptOwnerState>K7</rptOwnerState>
            <rptOwnerZipCode>400063</rptOwnerZipCode>
            <rptOwnerStateDescription>INDIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001717322</rptOwnerCik>
            <rptOwnerName>Sun Pharma (Netherlands) B.V.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>POLARISAVENUE 87</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOOFDDORP</rptOwnerCity>
            <rptOwnerState>P7</rptOwnerState>
            <rptOwnerZipCode>2132 JH</rptOwnerZipCode>
            <rptOwnerStateDescription>NETHERLANDS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001721949</rptOwnerCik>
            <rptOwnerName>Sun Pharmaceutical Industries, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>270 PROSPECT PLAINS ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CRANBURY</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08512</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-11-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1810536</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1810536</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Sun Pharmaceutical Industries, Inc.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-11-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>357143</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>357143</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Sun Pharma (Netherlands) B.V.</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-11-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1810536</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Sun Pharmaceutical Industries, Inc.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the total number of shares of Common Stock received by Sun Pharmaceutical Industries, Inc. upon conversion of the Issuer's Series B Preferred Stock in connection with the closing of the Issuer's initial public offering.</footnote>
        <footnote id="F2">Sun Pharmaceutical Industries Limited (&quot;Sun Pharma&quot;) directly and indirectly owns all shares of Sun Pharmaceutical Industries, Inc., which is the registered owner of the securities. Sun Pharma may be deemed to beneficially own all of the shares of the Issuer held by Sun Pharmaceutical Industries, Inc.  Dilip S. Shanghvi is the controlling shareholder of Sun Pharma. Sun Pharma and Mr. Shanghvi disclaim beneficial ownership of the reported shares except to the extent of their respective pecuniary interests therein.</footnote>
        <footnote id="F3">Sun Pharma is the sole shareholder of Sun Pharma (Netherlands) B.V., which is the registered owner of the securities. Sun Pharma may be deemed to beneficially own all of the shares of the Issuer held by Sun Pharma (Netherlands) B.V.  Dilip S. Shanghvi is the controlling shareholder of Sun Pharma. Sun Pharma and Mr. Shanghvi disclaim beneficial ownership of the reported shares except to the extent of their respective pecuniary interests therein.</footnote>
        <footnote id="F4">All series of the Issuer's Series B Preferred Stock automatically converted into the Issuer's Common Stock on a 7.180193-for-1 basis on November 21, 2017.  The Series B Preferred Stock had no expiration date.</footnote>
    </footnotes>

    <remarks>Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Dilip S. Shanghvi</signatureName>
        <signatureDate>2017-11-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jeremy Barr, Attorney-in-Fact (on behalf of Sun Pharmaceutical Industries Limited)</signatureName>
        <signatureDate>2017-11-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jeremy Barr, Attorney-in-Fact (on behalf of Sun Pharmaceutical Industries, Inc.)</signatureName>
        <signatureDate>2017-11-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jeremy Barr, Attorney-in-Fact (on behalf of Sun Pharma (Netherlands) B.V.)</signatureName>
        <signatureDate>2017-11-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
