| Cover | Nov. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 9, 2021 |
| Entity File Number | 001-36351 |
| Entity Registrant Name | PLx Pharma Inc. |
| Entity Central Index Key | 0001497504 |
| Entity Tax Identification Number | 46-4995704 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 9 Fishers Lane |
| Entity Address, Address Line Two | Suite E |
| Entity Address, City or Town | Sparta |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07871 |
| City Area Code | (973) |
| Local Phone Number | 409-6541 |
| 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 |
| Trading Symbol | PLXP |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
