A meta-analysis of 107 population-based studies found that dual use of e-cigarettes and cigarettes was associated with higher odds of several diseases than smoking alone. Compared to exclusive smokers, dual users had consistently higher odds of cardiovascular disease, stroke, metabolic dysfunction, asthma, COPD, and oral disease. The study also highlighted the need for reassessing the assumption that e-cigarette use provides harm reduction across all cigarette-caused diseases, especially considering dual use.

Source: NEJM Evidence