A comprehensive review of global research on smoking cessation suggests that e-cigarettes containing nicotine may help more people quit smoking than other commonly used methods. These include nicotine replacement therapy (nicotine patches, gum, lozenges, etc.) as well as non-nicotine e-cigarettes and behavioral support programs.
The analysis brings together findings from multiple systematic reviews to provide a clearer picture of what works best for quitting smoking. In total, researchers combined results from fourteen systematic reviews conducted between 2014 and 2023, making the evidence easier to interpret and compare.
Strongest Evidence Favors Nicotine E-Cigarettes
When focusing on the highest-quality studies, the results consistently show that nicotine e-cigarettes lead to higher quit rates than other approaches. In contrast, lower-quality studies produced less consistent and more uncertain findings. Overall, the most reliable evidence points to nicotine e-cigarettes outperforming nicotine replacement therapy, non-nicotine e-cigarettes, and other alternatives.
As part of the project, researchers developed an ‘Evidence and Gap Map’ (EGM) to highlight areas where more research is needed. Currently, there are no high-quality systematic reviews directly comparing nicotine e-cigarettes with treatments such as cytisine, bupropion, or nicotine pouches. Evidence comparing e-cigarettes with varenicline is also very limited, based on just one small study with a high risk of bias.
The EGM also indicates that evidence on serious adverse events linked to e-cigarettes remains uncertain. In addition, most of the available data comes from high-income countries. Researchers emphasize the need for future studies to better track potential risks and to include populations from low-and middle-income countries.
Researchers Say Evidence Is Clear
Lead author Dr. Angela Difeng Wu, Senior Researcher and Lecturer at the Nuffield Department of Primary Care Health Sciences, University of Oxford, says “We hope this overview and Evidence and Gap Map can lay to rest some claims that evidence is ‘mixed’ regarding the impacts of nicotine e-cigarettes on smoking abstinence. In fact, the evidence is clear and consistent across all of the meta-analyses we consulted: e-cigarettes are effective at helping people stop smoking.”
This research work was funded by Cancer Research UK, Grant Number PRCPJT‐Nov22/100012.