Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 28, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	Evoke Pharma Inc
Entity Central Index Key	0001403708
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 43.1
Entity Common Stock, Shares Outstanding		32,917,901
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	EVOK
Security Exchange Name	NASDAQ
Entity File Number	001-36075
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8447886
Entity Address, Address Line One	420 Stevens Avenue
Entity Address, Address Line Two	Suite 370
Entity Address, City or Town	Solana Beach
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92075
City Area Code	858
Local Phone Number	345-1494
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A in connection with the registrant’s 2021 Annual Meeting of Stockholders, which will be filed subsequent to the date hereof, are incorporated by reference into Part III of this Form 10-K. Such proxy statement will be filed with the Securities and Exchange Commission not later than 120 days following the end of the registrant’s fiscal year ended December 31, 2021.
Auditor Firm ID	243
Auditor Name	BDO USA, LLP
Auditor Location	San Diego, California