Intended for healthcare professionals

Letters Debate on e-cigarettes

Potential risk of carcinogens in e-cigarette vapour

BMJ 2015; 351 doi: (Published 24 September 2015) Cite this as: BMJ 2015;351:h5004
  1. Ricardo J José, specialty registrar and clinical research fellow in respiratory medicine1
  1. 1Centre for Inflammation and Tissue Repair, University College London, London WC1E 6JF, UK
  1. r.jose{at}

The recent Public Health England evidence update on e-cigarettes is an important review by experts that will certainly guide public health policy in the UK.1 However, although the use of e-cigarettes is currently perceived to be less harmful than smoking, e-cigarettes are not without risk. Albeit in lower concentrations than in cigarette smoke, e-cigarette solutions contain carcinogens such as formaldehyde and acetaldehyde, which are present in much greater concentrations when high voltage devices are used.2 In addition to the risk of oral and lung cancer from inhalation of these compounds, in preclinical experimental models e-cigarette vapour is associated with increased inflammation, oxidative stress, and disruption of endothelial barrier function.3 Furthermore, these effects on the airway may promote allergen induced airway hyper-reactivity.4 They may also predispose people to respiratory virus and bacterial infection by impairing immune function and enhancing the virulence of pathogens such as meticillin resistant Staphylococcus aureus.5 6 7

Further basic science and epidemiological research is needed to increase our evidence base on the benefits and harms of e-cigarette vapour. Until then patients should not be misled into thinking that the likelihood of future harm is negligible when there is insufficient evidence to advocate this.


Cite this as: BMJ 2015;351:h5004


  • Competing interests: None declared.


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