From the Research
Cannabis use is associated with an increased risk of syncope, particularly among adolescents and young adults, due to its effects on blood pressure and heart rate, as evidenced by a recent study published in 2025 1.
Relationship Between Cannabis Use and Syncope
The relationship between cannabis use and syncope is complex, with multiple factors contributing to the increased risk of fainting.
- Cannabis can cause orthostatic hypotension, where blood pressure drops significantly when standing up quickly, leading to reduced blood flow to the brain and potentially syncope.
- THC, the main psychoactive component in cannabis, can cause peripheral vasodilation, reducing blood return to the heart and decreasing blood pressure.
- Cannabis can also cause tachycardia (increased heart rate), which may exacerbate these effects.
Clinical Implications
People with pre-existing cardiovascular conditions are at higher risk of cannabis-related syncope.
- To prevent cannabis-related syncope, users should start with low doses, avoid standing up quickly after use, stay hydrated, and avoid combining cannabis with alcohol or other substances that lower blood pressure.
- If someone experiences repeated episodes of syncope after cannabis use, they should consider discontinuing use and consult a healthcare provider to rule out underlying cardiovascular issues, as suggested by a study published in 2023 2.
Evidence-Based Recommendations
The most recent and highest quality study on this topic, published in 2025 1, found that syncope is a prevalent condition among adolescents and young adults seeking treatment in emergency departments for cannabis-associated injuries.
- The study suggests that the clinical relevance of cannabis-associated syncope as it pertains to cardiovascular anomalies needs further study.
- As cannabis legislation, usage patterns, and products continue to evolve, a well-informed medical care community will be essential to address the potential health implications of cannabis use, including syncope.