| Cover | Jun. 24, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jun. 24, 2021 |
| Entity File Number | 001-38709 |
| Entity Registrant Name | Osmotica Pharmaceuticals plc |
| Entity Central Index Key | 0001739426 |
| Entity Tax Identification Number | 00-0000000 |
| Entity Incorporation, State or Country Code | L2 |
| Entity Address, Address Line One | 400 Crossing Boulevard |
| Entity Address, City or Town | Bridgewater |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 08807 |
| City Area Code | 908 |
| Local Phone Number | 809-1300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Ordinary Shares |
| Trading Symbol | OSMT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | true |
