Electronic cigarettes for smoking cessation.

Abstract

Electronic cigarettes (EC) are handheld electronic vaping devices that produce an aerosol by heating a liquid. People who smoke, healthcare providers, and regulators want to know if EC can help people quit smoking, and if they are safe to use for this purpose. This update was conducted as part of a living systematic review. To examine the safety, tolerability, and effectiveness of EC for helping people who smoke tobacco achieve long-term smoking abstinence, in comparison to non-nicotine EC, other smoking cessation treatments, and no treatment. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 January 2026, reference-checked, and contacted study authors. We included randomised controlled trials (RCTs) randomising people who smoked to an EC or control condition. Studies had to measure an eligible outcome. Critical outcomes were abstinence from smoking after at least six months, adverse events (AEs), and serious adverse events (SAEs). Important outcomes were biomarkers, toxicants/carcinogens, long-term study product use and long-term patterns of EC and combustible cigarette use. We used the RoB 1 tool to assess risk of bias for each study and GRADE to assess evidence certainty. We followed standard Cochrane methods for screening and data extraction. Where appropriate, we pooled data using random-effects models to calculate risk ratios (RRs) with 95% confidence intervals (CI) for dichotomous outcomes apart from SAEs. For SAEs, we calculated risk differences (RD) and 95% CI. For continuous outcomes, we calculated mean differences (MD) or standardised mean differences (SMD) with 95% CIs. We included 80 completed RCTs, representing 29,861 participants. Nine of these RCTs were new to this update. We rated 12 included studies as being at low risk of bias, 41 at high risk, and the remainder at unclear risk overall. Nicotine EC result in increased quit rates compared to nicotine replacement therapy (NRT) (high-certainty evidence) (RR 1.61, 95% CI 1.23 to 2.12; I² = 55%; 11 studies, 4114 participants). In absolute terms, this might translate to an additional four quitters per 100 (95% CI 1 to 7 more). The proportion of participants experiencing AEs may be similar between groups (low-certainty evidence, limited by imprecision and inconsistency) (RR 0.95, 95% CI 0.72 to 1.24; I² = 72%; 8 studies, 3107 participants) and the proportion of participants experiencing SAEs is probably similar between groups (moderate-certainty evidence, limited by imprecision) (RD 0.01, 95% CI -0.01 to 0.02; I² = 0%; 10 studies, 4045 participants). Nicotine EC probably result in increased quit rates compared to non-nicotine EC (moderate-certainty evidence, limited by imprecision) (RR 1.34, 95% CI 1.05 to 1.69; I² = 0%; 7 studies, 1918 participants). In absolute terms, this might lead to an additional two quitters per 100 (95% CI 0 to 4 more). There is probably little to no difference in the proportion of participants experiencing AEs between these groups (moderate-certainty evidence, limited by imprecision) (RR 1.01, 95% CI 0.95 to 1.08; I² = 0%; 6 studies, 909 participants) and there may be similar proportions of SAEs (RD 0.00, 95% CI -0.01 to 0.01; I² = 0%; 11 studies, 1786 participants; low-certainty evidence downgraded due to very serious imprecision). Compared to behavioural support only or no support, quit rates may be higher for participants randomised to nicotine EC (low-certainty evidence due to risk of bias) (RR 1.75, 95% CI 1.39 to 2.20; I² = 13%; 11 studies, 7214 participants). In absolute terms, this represents an additional two quitters per 100 (95% CI 2 to 6 more). There was some evidence that people randomised to nicotine EC may be more likely to experience (non-serious) AEs (RR 1.22, 95% CI 1.00 to 1.49; I² = 58%; 11 studies, 2801 participants; very low-certainty evidence due to imprecision and risk of bias), but the evidence is uncertain. There was insufficient evidence to determine whether rates of SAEs differed between groups (RD 0.00, 95% CI -0.00 to 0.01; I² = 0%; 18 studies, 5032 participants; very low-certainty evidence downgraded due to imprecision and risk of bias). There is high-certainty evidence that nicotine EC increase quit rates compared to NRT, and moderate-certainty evidence that they probably increase quit rates compared to EC without nicotine. Evidence comparing nicotine EC with behavioural support or no support also suggests benefit, but is less certain due to risk of bias inherent in the study designs. Overall incidence of SAEs was low across all study arms and there is now moderate-certainty evidence that SAE rates are similar when comparing nicotine EC with NRT. There was also no evidence of a difference in AEs between nicotine and non-nicotine EC nor between nicotine EC and NRT, but low-certainty evidence for increased AEs compared with behavioural support/no support. We did not detect evidence of serious short-term harm from nicotine EC, but longer, larger trials are needed to fully evaluate safety. The included studies tested regulated nicotine-containing EC; illicit products and/or products containing other active substances (e.g. tetrahydrocannabinol (THC)) may have different harm profiles. The main limitation of the evidence base remains imprecision for some comparisons. Further RCTs are underway. To ensure the review continues to provide up-to-date information, this is a living systematic review. We run and screen searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the most recent version of this review. Cancer Research UK (PICCTR-2024/100012). The addition of new outcomes relating to vaping and smoking at six months or more was supported by the National Cancer Institute of the National Institutes of Health (NIH) and FDA Center for Tobacco Products (CTP) under Award Number 2U54CA229974. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the Food and Drug Administration. The funders were not involved in the decision to submit for publication. Protocol (2012) available via DOI: 10.1002/14651858.CD010216 (updates to 2012 protocol available via https://osf.io/upgjc/overview.