| Document and Entity Information - USD ($) $ in Millions | 12 Months Ended | ||
| Sep. 30, 2023 | Jan. 10, 2024 | Mar. 31, 2023 | |
| Document and Entity Information [Abstract] | |||
| Document Type | 10-K/A | ||
| Document Annual Report | true | ||
| Document Period End Date | Sep. 30, 2023 | ||
| Document Transition Report | false | ||
| Entity File Number | 001-37759 | ||
| Entity Registrant Name | OUTLOOK THERAPEUTICS, INC. | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity Tax Identification Number | 38-3982704 | ||
| Entity Address, Address Line One | 485 Route 1 South | ||
| Entity Address, Adress Line Two | Building F, Suite 320 | ||
| Entity Address, City or Town | Iselin | ||
| Entity Address State Or Province | NJ | ||
| Entity Address, Postal Zip Code | 08830 | ||
| City Area Code | 609 | ||
| Local Phone Number | 619-3990 | ||
| Title of 12(b) Security | Common Stock | ||
| Trading Symbol | OTLK | ||
| Security Exchange Name | NASDAQ | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | false | ||
| ICFR Auditor Attestation Flag | false | ||
| Entity Shell Company | false | ||
| Entity Common Stock, Shares Outstanding | 260,257,517 | ||
| Entity Public Float | $ 179.5 | ||
| Entity Central Index Key | 0001649989 | ||
| Current Fiscal Year End Date | --09-30 | ||
| Document Fiscal Year Focus | 2023 | ||
| Document Fiscal Period Focus | FY | ||
| Amendment Flag | false | ||
| Auditor Name | KPMG LLP | ||
| Auditor Location | Philadelphia, Pennsylvania | ||
| Auditor Firm ID | 185 |
