Document and Entity Information - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Feb. 23, 2026 |
Jun. 30, 2025 |
|
| Cover [Abstract] | |||
| Document Type | 10-K | ||
| Amendment Flag | false | ||
| Document Period End Date | Dec. 31, 2025 | ||
| Document Fiscal Year Focus | 2025 | ||
| Document Fiscal Period Focus | FY | ||
| Trading Symbol | AMLX | ||
| Entity Registrant Name | Amylyx Pharmaceuticals, Inc. | ||
| Entity Central Index Key | 0001658551 | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity File Number | 001-41199 | ||
| Entity Tax Identification Number | 46-4600503 | ||
| Entity Address, Address Line One | 55 Cambridge Parkway | ||
| Entity Address, Address Line Two | Suite 6W | ||
| Entity Address, City or Town | Cambridge | ||
| Entity Address, State or Province | MA | ||
| Entity Address, Postal Zip Code | 02142 | ||
| City Area Code | 617 | ||
| Local Phone Number | 682-0917 | ||
| Entity Current Reporting Status | 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 | ||
| Entity Shell Company | false | ||
| Entity Common Stock, Shares Outstanding | 110,536,944 | ||
| Entity Public Float | $ 518.2 | ||
| Entity Interactive Data Current | Yes | ||
| Title of 12(b) Security | Common Stock, $0.0001 par value per share | ||
| Security Exchange Name | NASDAQ | ||
| Entity Incorporation, State or Country Code | DE | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| ICFR Auditor Attestation Flag | false | ||
| Document Financial Statement Error Correction [Flag] | false | ||
| Auditor Name | Deloitte & Touche LLP | ||
| Auditor Location | Boston, Massachusetts | ||
| Auditor Firm ID | 34 | ||
| Documents Incorporated by Reference | DOCUMENTS INCORPORATED BY REFERENCE The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2026 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2025. Portions of such definitive proxy statement for the 2026 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein. |
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| Auditor Opinion [Text Block] | Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Amylyx Pharmaceuticals, Inc. and subsidiaries (the “Company”) as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive loss, stockholders’ equity, and cash flows, for each of the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the years then ended, in conformity with accounting principles generally accepted in the United States of America. |