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  • Team: Jamie Hartmann-Boyce
  • Theme: Therapeutics
  • Ongoing projects

Background context:

Since coming on the market over a decade ago, electronic cigarettes have caused a considerable stir in the public health community. Jamie Hartmann-Boyce, CEBM researcher, and co-director of the EBHC DPhil programme, leads the Cochrane review ( of electronic cigarettes for smoking cessation, to evaluate the safety and effect of using ECs to help people who smoke achieve long‐term smoking abstinence.

Key findings:

Combined results from two studies, involving 662 people, showed that using an EC containing nicotine increased the chances of stopping smoking in the long term compared to using an EC without nicotine. We could not determine if EC was better than a nicotine patch in helping people stop smoking, because the number of participants in the study was low. More studies are needed to evaluate this effect. The other studies were of lower quality, but they supported these findings. None of the studies found that smokers who used EC short‐ to mid‐term (for two years or less) had an increased health risk compared to smokers who did not use ECs.


A limited number of randomized trials have been reported, so certainty about the effects is low. More data are needed to strengthen confidence in the estimates. There is evidence from the pooled results of two trials that electronic cigarettes (ECs) with nicotine, compared with placebo ECs, helped smokers to stop smoking long‐term. This corresponds to findings from placebo‐controlled trials of NRT (Stead 2012).

There is evidence from one trial that ECs may lead to six‐month quit rates similar to those achieved with NRT, but the confidence interval is wide. ECs are an evolving technology and the effects of newer devices with better nicotine delivery are unknown.

None of the included studies (short‐ to mid‐term, up to two years) detected serious adverse events considered possibly related to EC use. The most commonly reported adverse effects were irritation of the mouth and throat. The long‐term safety of ECs is unknown. In some studies, reductions in biomarkers were observed in smokers who switched to vaping consistent with reductions seen in smoking cessation.


Since it’s first publication in 2014, this review has contributed to national and international guidelines. There is a huge amount of misinformation circulating about electronic cigarettes, and Jamie has been actively involved in sharing the evidence with diverse audiences. This includes media interviews, as well as blogs, resources for clinicians (, and even performing a song about vaping on the streets of Oxford. 

What's next:

An update of the review is underway and will come out in autumn 2020, at which point, with support from Cancer Research UK, the review will be regularly updated, with searches run monthly to ensure decision-makers have the most up to date evidence to hand.

Further reading:

if you’re interested in reading more about the evidence on e-cigarettes, you might want to look at Jamie’s recent article in The Conversation about an important retraction: Jamie has also written about the controversies surrounding electronic cigarettes in the Guardian: and has recently spoken about why reviews in this area often come up with conflicting findings:

If you’re interested in hearing the song about the evidence on e-cigarettes, you can watch the video here:, and learn more about the evidence and process behind the song here: