v3.21.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2021
May 03, 2021
Document and Entity Information    
Document Type 10-Q  
Document Period End Date Mar. 31, 2021  
Entity Registrant Name Milestone Pharmaceuticals Inc.  
Title of 12(b) Security Common Shares  
Trading Symbol MIST  
Security Exchange Name NASDAQ  
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  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   29,846,000
Entity Central Index Key 0001408443  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q1  
Amendment Flag false