E-cigarettes are a potential smoking cessation aid and they may also be able to lower the risk of nicotine dependency in high-risk groups. A systematic literature search for data on e-cigarettes' mechanism of action, their emissions, how they are seen by groups of potential users, their efficacy in smoking cessation, and their addiction potential finds that more studies will have to be done to know for sure. 

According to surveys, e-cigarettes are used by younger people, those with higher incomes, and heavier smokers. Among e-cigarette users, 85% reported that they used them to stop smoking. According to repeat surveys in the U.K., the number of people who were aware of e-cigarettes doubled between 2010 and 2012, and the number of users increased four-fold.

An online survey of e-cigarette users found that 74% of those asked had not smoked tobacco for at least several weeks since using e-cigarettes, and 70% reported reduced cigarette cravings. However, there is evidence that people who have never previously smoked also use e-cigarettes. The rates among Polish and US students, for example, were 3% and 9% respectively.

Two controlled trials showed e-cigarettes as having similar effects to nicotine replacement therapies as smoking cessation aids and these effects were almost independent of nicotine content. 

Writing in
Deutsches Ärzteblatt International (Dtsch Arztebl Int 2014; 111: 349–55), Dennis Nowak and colleagues call for more randomized trials to be conducted.