Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 10, 2022
Document and Entity Information
Document Type	10-Q
Document Period End Date	Sep. 30, 2022
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-38899
Entity Registrant Name	Milestone Pharmaceuticals Inc.
Entity Incorporation, State or Country Code	A8
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	1111 Dr. Frederik-Philips 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 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		34,286,002
Entity Central Index Key	0001408443
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false