v3.23.1
Cover - USD ($)
$ in Millions
Dec. 31, 2022
Mar. 29, 2023
Jun. 30, 2022
Cover [Abstract]      
Document Type 10-K/A    
Amendment Flag false    
Document Annual Report true    
Document Transition Report false    
Document Period End Date Dec. 31, 2022    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2022    
Current Fiscal Year End Date --12-31    
Entity File Number 001-38899    
Entity Registrant Name Milestone Pharmaceuticals Inc.    
Entity Central Index Key 0001408443    
Entity Tax Identification Number 00-0000000    
Entity Incorporation, State or Country Code A8    
Entity Address, Address Line One 1111 Dr. Frederik-Phillips Boulevard    
Entity Address, Address Line Two Suite 420    
Entity Address, City or Town Montréal    
Entity Address, State or Province QC    
Entity Address, Postal Zip Code H4M 2X6    
City Area Code 514    
Local Phone Number 336-0444    
Title of 12(b) Security Common Shares    
Trading Symbol MIST    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company true    
Elected Not To Use the Extended Transition Period true    
Entity Shell Company false    
Entity Public Float     $ 184.5
Entity Common Stock, Shares Outstanding   33,287,226  
ICFR Auditor Attestation Flag false    
Auditor Firm ID 271    
Auditor Name PricewaterhouseCoopers LLP    
Auditor Location Montréal, Canada