| Document And Entity Information | Nov. 09, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 09, 2022 |
| Entity Registrant Name | Evoke Pharma, Inc. |
| Entity Central Index Key | 0001403708 |
| Entity Emerging Growth Company | false |
| Securities Act 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, 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | EVOK |
| Security Exchange Name | NASDAQ |
