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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2020-10-08</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001683553</issuerCik>
        <issuerName>SPRUCE BIOSCIENCES, INC.</issuerName>
        <issuerTradingSymbol>SPRB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001783281</rptOwnerCik>
            <rptOwnerName>HealthCap VIII, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>AVENUE D?OUCHY 18</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LAUSANNE</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>CH-1006</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1783621</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The shares of Series B Preferred Stock (&quot;Series B Preferred&quot;) have no expiration date and are convertible at any time at the election of the holder without payment of further consideration. Each share of Series B Preferred will automatically convert into 0.152881822351322 shares of Common Stock upon the closing of the Issuer's initial public offering.</footnote>
        <footnote id="F2">Share numbers give effect to the reverse split of each share of the Issuer's Common Stock into 0.152881822351322 shares of Common Stock effected on October 2, 2020, which will be effective for the Preferred Stock upon its conversion to Common Stock upon the closing of the Issuer's initial public offering.</footnote>
        <footnote id="F3">The shares are directly held by HealthCap VIII, L.P. (&quot;HCLP&quot;).  HealthCap VIII GP SA (&quot;HCSA&quot;) is the sole general partner of HCLP and has voting and investment control over such shares held by HCLP.  Jonas Hansson, a Director of the Issuer, has an indirect interest in HCSA and is an employee of Health Cap VIII Advisor AB.  Each of the General Partner and Mr. Hansson disclaims beneficial ownership of such securities, except to the extent of his/its indirect pecuniary interest therein, and this report shall not be deemed an admission that the General Partner or Mr. Hansson is the beneficial owner of such shares.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>HealthCap VIII L.P., by HealthCap VIII GP SA, it's general partner, By: /s/ Dag Richter, Director and By: /s/ Fabrice Berhard, General Manager</signatureName>
        <signatureDate>2020-10-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
