| Cover | Aug. 11, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 11, 2022 |
| Entity File Number | 001-38738 |
| Entity Registrant Name | Eton Pharmaceuticals, Inc. |
| Entity Central Index Key | 0001710340 |
| Entity Tax Identification Number | 37-1858472 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 21925 W. Field Parkway |
| Entity Address, Address Line Two | Suite 235 |
| Entity Address, City or Town | Deer Park |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60010-7278 |
| City Area Code | (847) |
| Local Phone Number | 787-7361 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | ETON |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | true |
