E-cigarettes
E-cigarettes, or vapes, heat a nicotine liquid instead of burning tobacco. For smokers trying to quit, high-certainty trial evidence shows they help more people stop than nicotine replacement such as patches or gum, but they are not harmless: vaping raises heart rate and blood pressure in the short term, and nobody yet knows what decades of use do.
If you smoke, a nicotine e-cigarette is a reasonable way to quit, as long as you switch completely and plan to stop vaping too. If you don't smoke, don't start.
What they are
E-cigarettes (electronic nicotine-delivery systems) heat a liquid, usually based on propylene glycol, on a metal coil. There is no combustion, so the tar and carbon monoxide of cigarette smoke are absent, but heating the liquid produces aldehydes such as formaldehyde, and the coils shed heavy metals including nickel, lead and chromium. See Smoking and nicotine for how vapes compare with cigarettes, pouches and patches.
They help smokers quit
For smokers trying to stop, high-certainty evidence shows nicotine e-cigarettes help more people quit than conventional nicotine replacement.[1] The 2026 update of that living review (80 trials) confirms the advantage at high certainty, with serious side effects rare in all trial arms.[2] A network meta-analysis of all the quitting options ranks nicotine e-cigarettes among the most effective, alongside varenicline, cytisine and combination nicotine replacement.[3] These trials tested regulated nicotine vapes used for quitting, not long-term recreational use.
What vaping does to the heart and lungs
Right after a vaping session, heart rate rises by about 1.4 beats per minute and blood pressure by about half a mm Hg, and blood markers of blood-vessel-lining activation and platelet stickiness go up. Vaping is also linked to about 1.3 times the odds of asthma.[4]
Whether this adds up to heart attacks and strokes is not yet known. Cohorts followed for about four years have not shown a clear rise in heart attacks, strokes or heart failure in people who only vape, but follow-up is short and events are few. People who both vape and smoke carry roughly smoking-level cardiovascular risk, so a switch has to be complete.[5][6]
The "95% less harmful" figure is not a measurement
The much-repeated claim that vaping is "95% less harmful than smoking" traces to a 2014 expert-judgment scoring exercise, amplified by a 2015 Public Health England review. It has been sharply criticised as a "factoid" resting on thin evidence and a partly non-transparent funding source.[7][8] Treat it as a contested estimate, not a fact.
The 2019 lung-injury outbreak
The 2019–2020 outbreak of e-cigarette or vaping use-associated lung injury (EVALI) was overwhelmingly caused by vitamin E acetate added as a diluent to illicit THC cartridges. It was found in the lung-lavage fluid of 48 of 51 cases and none of the healthy controls, rather than being an intrinsic hazard of regulated nicotine e-liquid.[9]
Who should be careful
- People who don't smoke. Vaping is less bad than smoking, not safe. There is no case for taking it up.
- Teenagers. In rodents, adolescent nicotine exposure permanently changes the hippocampus and predisposes to later depression and learning problems, mirroring the relapse and cognitive signals in people who start young.[10] Vaping marketed to teenagers is a public-health failure, not harm reduction.
- Pregnancy. Obstetric guidance is to advise stopping every tobacco product, e-cigarettes included.[11]
- Dual users. Vaping while still smoking keeps most of the cardiovascular risk of smoking.
- Anyone vaping to lose weight. Nicotine drives insulin resistance and is linked to metabolic syndrome and type 2 diabetes; it is a worse trade than other ways to manage weight.
What to do
- If you smoke and want to quit, a nicotine e-cigarette is one of the most effective options. Switch completely; don't use it alongside cigarettes.
- Plan an exit. Use it as a quitting tool, not a permanent habit.
- Use regulated nicotine products only, never illicit THC cartridges.
- If you don't smoke, don't start, and keep vapes away from teenagers.
Further reading
- Lindson N et al. Electronic cigarettes for smoking cessation. Cochrane Database Syst Rev 2026.[12]
- Kaur J et al. Health impacts of electronic nicotine delivery systems: an umbrella review of systematic reviews. BMJ Open 2025.[13]
- Erhabor J et al. E-cigarette Use and Incident Cardiometabolic Conditions in the All of Us Research Program. Nicotine Tob Res 2025.[14]
- Berlowitz JB et al. E-Cigarette Use and Risk of Cardiovascular Disease: A Longitudinal Analysis of the PATH Study (2013-2019). Circulation 2022.[15]
- Blount BC et al. Vitamin E acetate in bronchoalveolar-lavage fluid associated with EVALI. N Engl J Med 2020.[16]