What do we currently know about electronic cigarettes?

publicinfo_MattWall-eCigs1Nicotine is one of the most widely-used drugs in the world, and the way in which most people consume it is in the form of cigarettes or other tobacco products. Smoking tobacco is one of the worst things that someone can do for their long-term health; smoking contributes to a range of cardiovascular and respiratory diseases and, of course, directly causes lung cancer.

Recently though, a new class of nicotine containing products has hit the market: electronic cigarettes. These don’t contain tobacco; instead the nicotine is held in a liquid, which is vaporised by a small heating element powered by a battery. The vapour is then inhaled in the same manner as tobacco smoke. These products come in a massive variety of shapes and sizes, ranging from small ones that look like cigarettes, to large, very powerful devices that can produce huge clouds of vapour.

Because these products are relatively new, we don’t know a great deal about their health effects, and their legal status is also somewhat uncertain. A bill to ban their use in certain public places in Wales was recently rejected by the Welsh assembly, but it’s likely that formal legal sanctions on their use will come in at some point. On the other hand, the MHRA (the Medicines and Healthcare products Regulatory Authority) recently granted a license to a specific manufacturer of e-cigarettes, meaning that they could technically now be prescribed on the NHS. The British Medical Association (BMA) says that it recognises the potential use of e-cigarettes in helping people to stop smoking, but that much more research is needed into their health effects.

This is definitely true. It takes time to conduct research, and we may need to track the effects on health over many years of use to understand what the risks (if any) are. There are also many issues surrounding e-cigarette use that need to be addressed. One major question that researchers have begun to address is whether e-cigarettes are actually helpful in getting people to stop smoking. Evidence from surveys [1] suggests that many e-cigarette users found them helpful when quitting smoking, while some other more controlled studies have also found that users of e-cigarettes are more successful at quitting, compared to traditional Nicotine Replacement Therapy (NRT; gum or patches) users, or those who use no aids to quitting [2]. However, a recent review of 20 studies found that overall, e-cigarette use was actually associated with less successfully quitting smoking [3]. Another review found a fairly modest trend towards e-cigarettes being helpful for quitting smoking [4]. At this point, it’s hard to say exactly how effective e-cigarettes are in helping people quit smoking, though it’s clear that at least some people find them useful.

What about the health effects? As noted above, we may need to wait a few more years before some health effects become apparent, but one thing that we can look at is the acute effect on the cardiovascular system. Several studies have found that use of an e-cigarette acutely increases heart-rate and blood pressure, and this is expected because of the general stimulant effect of nicotine. It’s possible that these effects could lead to longer-term cardiovascular problems. One recent study found that switching to e-cigarettes could lead to reductions in blood pressure, in those subjects whose blood pressure was elevated to start with. [5] Another large review of studies [6] was forced to conclude that the quality and quantity of available evidence was not sufficient to reach a firm conclusion about the health effects of e-cigarettes. What most authors agree on though, is that the dangers of e-cigarettes are likely to be very much less than traditional cigarettes, and this was highlighted by a report published by the ICSD [7] (Independent Scientific Committee on Drugs), which rated e-cigarettes as roughly 20 times less harmful than traditional cigarettes.

publicinfo_MattWall-eCigs2My own interest in e-cigarettes is much more practical; I’m using them as an experimental tool in brain research. Up until now it was difficult to see the brain processes happening when someone is smoking, because there are a lot of practical issues with smoking cigarettes in a brain scanner; the room fills up with smoke, lighting the cigarette is difficult, and there’s a chance that the subject could drop the cigarette and cause a fire. Also, most hospitals and universities have strict rules about smoking in their facilities! E-cigarettes don’t have these problems though, and we have been able to produce the first functional MRI (Magnetic Resonance Imaging) images of the brain response to subjects ‘smoking’ e-cigarettes. These show interesting results in areas in the centre of the brain, known to be involved in the processes of addiction and response to drugs. It’s hoped these results can lead to better understanding of how addiction to nicotine works, and perhaps inform better treatments.

In conclusion, while it’s likely that e-cigarettes are substantially safer than traditional cigarettes, it’s still too early to say exactly how dangerous or safe they are. It’s possible that switching from traditional cigarettes to e-cigarettes could lead to net positive health benefits, but at the moment they can’t be considered a healthy option for those who have never smoked. In addition, e-cigarettes are proving a useful additional tool in the study of the brain’s response to nicotine and smoking behaviour.


  1. Etter, J. F. (2015). Characteristics of users and usage of different types of electronic cigarettes: findings from an online survey. Addiction.
  2. Brown, J., Beard, E., Kotz, D., Michie, S., & West, R. (2014). Real‐world effectiveness of e‐cigarettes when used to aid smoking cessation: a cross‐sectional population study. Addiction, 109(9), 1531-1540.
  3. Kalkhoran, S., & Glantz, S. A. (2016). E-cigarettes and smoking cessation in real-world and clinical settings: a systematic review and meta-analysis. The Lancet Respiratory Medicine.
  4. Khoudigian, S., Devji, T., Lytvyn, L., Campbell, K., Hopkins, R., & O’Reilly, D. (2016). The efficacy and short-term effects of electronic cigarettes as a method for smoking cessation: a systematic review and a meta-analysis.International journal of public health, 1-11.
  5. Farsalinos, K., Cibella, F., Caponnetto, P., Campagna, D., Morjaria, J. B., Battaglia, E., … Polosa, R. (2016). Effect of continuous smoking reduction and abstinence on blood pressure and heart rate in smokers switching to electronic cigarettes. Internal and Emergency Medicine, 11(1), 1-10.
  6. Pisinger, C., & Døssing, M. (2014). A systematic review of health effects of electronic cigarettes. Preventive Medicine, 69, 248-260.
  7. Nutt, D. J., Phillips, L. D., Balfour, D., Curran, H. V., Dockrell, M., Foulds, J., … Sweanor, D. (2014). Estimating the Harms of Nicotine-Containing Products Using the MCDA Approach. European Addiction Research, 20(5), 218-225.

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