<SEC-DOCUMENT>0001280776-17-000059.txt : 20170609
<SEC-HEADER>0001280776-17-000059.hdr.sgml : 20170609
<ACCEPTANCE-DATETIME>20170609160647
ACCESSION NUMBER:		0001280776-17-000059
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170608
FILED AS OF DATE:		20170609
DATE AS OF CHANGE:		20170609

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			VITAL THERAPIES INC
		CENTRAL INDEX KEY:			0001280776
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		15010 AVENUE OF SCIENCE
		STREET 2:		STE. 200
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92128
		BUSINESS PHONE:		858-673-6840

	MAIL ADDRESS:	
		STREET 1:		15010 AVENUE OF SCIENCE
		STREET 2:		STE. 200
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92128

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Nash Duane
		CENTRAL INDEX KEY:			0001591098

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36201
		FILM NUMBER:		17902973

	MAIL ADDRESS:	
		STREET 1:		C/O VITAL THERAPIES, INC.
		STREET 2:		15010 AVENUE OF SCIENCE, SUITE 200
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92128
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149703879137117.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-06-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001280776</issuerCik>
        <issuerName>VITAL THERAPIES INC</issuerName>
        <issuerTradingSymbol>VTL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001591098</rptOwnerCik>
            <rptOwnerName>Nash Duane</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O VITAL THERAPIES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>15010 AVENUE OF SCIENCE, SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92128</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-06-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3900</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.1236</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8224</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $3.10 to $3.15.  The reporting person undertakes to provide Vital Therapies, Inc., any security holder of Vital Therapies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price range set forth in this footnote (1) to this Form 4.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Michael V. Swanson, by power of attorney</signatureName>
        <signatureDate>2017-06-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
