The short answer
Health Canada says THC can raise heart rate shortly after use and lists rapid or irregular heartbeat, chest pain and shortness of breath among serious side effects. The American Heart Association describes AFib signals in observational research but also emphasizes major evidence gaps. An association does not show that cannabis caused one person's AFib or predict an individual's risk.
What readers can take from the evidence
For chest pain, breathing difficulty or loss of consciousness, seek urgent medical help. For a rapid or irregular heartbeat after cannabis use, stop using cannabis and contact a health professional. Health Canada's January 2026 guide says to call 9-1-1 for a cannabis-related medical emergency. Do not use cannabis to treat AFib or change prescribed heart medicines based on an article. Bring product details and timing to a clinician if discussing an event. Adults over 55 and people with cardiovascular disease or multiple medicines may face added risks according to Health Canada. For medication questions, see our interaction overview.
Questions readers ask
Does cannabis cause AFib?
Current observational signals do not establish individual causation. Evidence is incomplete; this page cannot diagnose or estimate personal risk.
What symptoms should not wait?
Health Canada lists rapid or irregular heartbeat as a serious side effect and advises contacting a health professional. For chest pain, breathing difficulty or loss of consciousness, seek urgent medical help; its January 2026 guide says to call 9-1-1 for a cannabis-related medical emergency.
Sources
- Health Canada: Adults over 55
- American Heart Association: Scientific statement summary
- Health Canada: Information on the use of cannabis for medical purposes (January 2026)
Sources checked September 24, 2026.