Smokers who ‘dual use’ cigarettes and vapes cut toxin intake and are more likely to quit, QMUL study suggests

Smokers who use e-cigarettes alongside tobacco – known as “dual use” – reduce their intake of harmful chemicals and may be more likely to quit smoking altogether than those who continue to smoke only cigarettes, according to new research from Queen Mary University of London (QMUL).

The study, led by researchers at QMUL’s Wolfson Institute of Population Health, challenges the commonly held belief that dual use is inherently risky and should be discouraged. Instead, the authors argue it can represent a form of harm reduction for smokers who struggle to quit abruptly.

Researchers carried out a secondary analysis of data from a National Institute for Health and Care Research (NIHR) and Cancer Research UK (CRUK)-funded randomised controlled trial involving 886 adult smokers attempting to stop. The original trial compared e-cigarettes with nicotine replacement therapy (NRT) as quitting aids, and the new analysis focused on patterns of product use and smoking cessation outcomes over the course of a year.

The key finding was that dual use among participants who failed to stop smoking early in their quit attempt was linked to stopping smoking later. Even among those who did not ultimately quit, becoming a dual user was associated with substantial reductions in cigarette consumption and lower intake of tobacco toxicants.

The researchers also found e-cigarette users experienced lower urges to smoke than those using NRT, which could help explain why vaping supports cessation and why dual users may find it easier to cut down cigarettes over time.

In addition, most vapers in the trial started on higher nicotine strengths and gradually moved to lower strengths. By one year, around one in 10 e-cigarette users had shifted to nicotine-free e-liquids, suggesting vaping could offer smokers a route to taper nicotine consumption in stages.

Lead author Francesca Pesola said: “The sooner smokers quit the better, but for those who find it difficult to stop smoking abruptly, vaping can help with doing it gradually over time.”

Co-lead author Professor Peter Hajek added: “Smokers (and clinicians) sometimes believe that if smokers do not manage to stop smoking soon after starting vaping, they should stop using e-cigarettes to avoid ‘dual use’. These results show that dual use promotes genuine harm reduction and that it can be a useful step to stopping smoking altogether.”

The research, Patterns of e-cigarette use and smoking cessation outcomes: Secondary analysis of a large RCT to inform clinical advice, was published in Nicotine & Tobacco Research.