Vaping may raise the risk of stroke and heart attack, a review of more than 1.5 million people suggests.
The findings challenge the idea that e-cigarettes are a safe alternative to tobacco.
Researchers ran a systematic review and meta-analysis (a pooled analysis of multiple studies) of 12 observational studies and randomised trials published between January 2005 and June 2025.
For stroke outcomes, the analysis included 121,113 e-cigarette users and 1,064,228 non-users; for heart attack outcomes, 67,253 users and 363,622 non-users.
E-cigarette users had a 1.53-fold higher risk of heart attack than non-users, and a 1.24-fold higher risk after adjusting for cigarette smoking.
Risk was notably higher among current e-cigarette users who were former cigarette smokers, showing a 2.52-fold increase in heart attack risk.
Stroke risk was slightly higher among e-cigarette users overall (meta-OR 1.05); former smokers using e-cigarettes had a 1.73-fold increased risk of stroke compared with non-users.
The study highlights the need for well-designed longitudinal research to define cardiovascular effects and guide policy.
Clinicians are advised to counsel patients on potential risks from e-cigarettes, particularly those with a history of conventional cigarette use.
