Question & Answer

Does vaping or e-cigarettes make a difference to health?

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The Evidence

  • Vaping has become very popular with smokers to help them quit, and with non-smokers – including young people. Given the popularity of e-cigarettes, there are many questions about the way they are regulated and their impacts on health.
  • Many e-cigarettes contain nicotine, and people who smoke regular cigarettes often use them to help them stop because they are seen as a safer alternative.
  • We found 23 relevant systematic reviews. Some compared the health of e-cigarette users to people who smoke regular cigarettes or people who use both. Others compared them with non-smokers. Reviews comparing them to both found that e-cigarettes may be worse for you than not smoking, but do less harm than smoking regular cigarettes.
  • Most of the studies included in the reviews are observational. This means we can’t be sure it’s a fair comparison or say that e-cigarettes were the cause of any associations with poor health. The authors of most reviews concluded that e-cigarettes haven’t yet been on the market long enough to know their long-term impacts on health and that better quality studies are needed.
  • The reviews looked at how e-cigarettes affect different aspects of health:
    1. General health: One high-quality review and another of low-quality looked at the impact of e-cigarettes on various aspects of health (inflammation, immune response, oral health, lung function, lung health, and cardiovascular disease). Some of the studies found negative impacts of using e-cigarettes, some didn’t, and many were uncertain.
    2. Second-hand vaping: We found very little information about the risks of being around others who vape (second-hand exposure). Only one low-quality review specifically mentioned it and reported that one study found it may be associated with asthma symptoms in young people.
    3. Lung health: Six systematic reviews focused on the link between e-cigarettes and lung health. Two high-quality reviews, one in smokers and another in non-smokers, found that most studies have not shown a difference in lung function between those who vape and those who don’t. However, two high-quality reviews (one in teenagers and one other) and two moderate-quality reviews found that people who used e-cigarettes were more likely to be diagnosed with lung disease, mostly asthma. The included studies had limitations, so it is difficult to be certain about the results.
    4. Cardiovascular health:  Eight systematic reviews, three that were high quality, looked at cardiovascular health. Overall people using e-cigarettes tended to have worse cardiovascular health than people who didn’t smoke (e.g. higher blood pressure), and either similar or better outcomes to people who smoke regular cigarettes. One high-quality review found that people who use e-cigarettes were more likely to have a heart attack than people who don’t, but the risk was still half that of those who smoke regular cigarettes.
    5. Quitting smoking: Four high-quality systematic reviews looked at the safety of e-cigarettes compared with other ways of quitting smoking, such as nicotine replacement therapy or counselling. None of the reviews found evidence of serious harm from e-cigarettes, with or without nicotine, compared with other options. The reviews included randomized controlled trials and other types of study, but few were good-quality studies. They did not include many people, and none were longer than 2 years.
    6. Cancer: One high-quality review found only low-quality evidence about the impact of e-cigarettes on head and neck cancers and highlighted that they have not been on the market long enough for reliable studies to have been done.

Guidelines and recommendations

  • The World Health Organization considers e-cigarettes harmful to health. In a 2020 statement, they highlighted that evidence about their impact on health is mounting, but devices have not been on the market long enough to fully understand their long-term effects. Their position is that e-cigarettes containing nicotine are “undoubtedly harmful, should be strictly regulated and, most importantly, must be kept away from children”, due to increased risks of cardiovascular diseases, lung disorders, and starting to smoke regular cigarettes.
  • NICE and Public Health England include e-cigarettes within their recommended options for quitting smoking and do not have guidance about their use by non-smokers.
  • HSE says they “are not confident that vaping is a safe or effective way to stop smoking and recommends other options”. They say “the best thing you can do for your health is not to smoke or vape” and that using e-cigarettes “may be less harmful” compared to cigarettes, but it “is not harm free”.

Things to Remember

  • Just because something is associated with people getting better or worse, doesn’t mean the treatment made them better or worse.
  • If one study shows that people who got one treatment did better or worse than people who got something else, it does not mean that is the final answer.


  • Lead Researcher: Dr. Kayleigh Kew, freelance evidence synthesis specialist with interests in technology, methods and innovation.
  • Reviewed by: Dr. Paula Byrne, Senior post-doctoral researcher, iHealthFacts, Evidence Synthesis Ireland and Cochrane Ireland, College of Medicine, Nursing and Health Sciences, University of Galway.
  • Topic advisor: Dr. Frank Moriarty, Senior Lecturer in Pharmacy at the School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland and visiting research fellow at The Irish Longitudinal Study on Ageing (TILDA).
  • Public and Patient advisor: Anne Daly, Public and Patient Involvement in research (PPI) advisor, PPI Ignite, University of Galway.
  • Journalist Advisor: Dr. Claire O’Connell, PhD in cell biology, Masters in Science Communication. Contributor to The Irish Times, writing about health, science and innovation.

Conflict of Interest Statement: The authors have no financial or other conflicts of interest for this health claim summary.