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E-cigarettes raise teens’ risk of persistent cough and wheeze, study finds

Teenagers who use e-cigarettes have twice the risk of respiratory symptoms such as persistent cough, bronchitis, and wheeze as those who have never used the devices, a large US study has found.1

Use of e-cigarettes among teenagers is increasing dramatically, and public health experts are concerned that these devices may increase cigarette smoking. But there has been limited information on the effect of chronic e-cigarette use on respiratory health.

Researchers analysed responses to a questionnaire from 2086 teenagers aged 16 to 18 years who were taking part in the ongoing Southern California Children’s Health study, to investigate the long term effects of air pollution on respiratory health in young people. Respondents to the 2014 questionnaire were asked about use of e-cigarettes and chronic cough, phlegm, bronchitis, and wheeze in the previous 12 months.

The results showed that the risk of bronchitic symptoms was twice as high in teenagers who said that they were currently using e-cigarettes as in those who had never tried them (odds ratio 2.02 (95% confidence interval 1.42 to 2.88)).

Risk of bronchitis symptoms rose with frequency of current use, from a two thirds higher risk in teenagers who used e-cigarettes for 1-2 days in the previous month (odds ratio 1.66 (1.02 to 2.68)) to two and a half times the risk in those using them on three or more days (odds ratio 2.52 (1.56 to 4.08)), when compared with never users.

And the risk of respiratory symptoms was 85% higher in teenagers who said that they had used e-cigarettes than in those who had never used them (odds ratio 1.85 (1.37 to 2.49)). This increased risk remained even after adjustment for relevant potential confounding factors. Associations were slightly reduced when data were adjusted for lifetime number of cigarettes smoked and secondhand smoke exposure. But the risk of bronchitic symptoms among past e-cigarette users remained higher after adjustment for relevant potential confounders and was also seen among those who had never smoked cigarettes (odds ratio 1.70 (1.11 to 2.59)).

Just under a 10th (9.6% (201)) of the adolescents who responded to the survey were current users of e-cigarettes, having used them at least once in the previous 30 days.

An eighth (14.4%) were past users, reporting that they had used e-cigarettes previously but not in the past month. And three quarters (76%) said that they had never used e-cigarettes.

“E-cigarettes are known to deliver chemicals toxic to the lungs, including oxidant metals, glycerol vapour, diketone flavouring compounds, and nicotine,” said the study’s lead author, Rob McConnell, professor of preventive medicine at the Keck School of Medicine at the University of Southern California, Los Angeles.

He noted, “The Food and Drug Administration recently banned the sale of e-cigarettes to children under 18 years of age, and California just prohibited sale to young adults under 21.

“Our results suggest that these regulations and an environment that discourages the initiation of any tobacco product may reduce the burden of chronic respiratory symptoms in youth.” He added that further studies were needed to better understand the long term effects of e-cigarette use.

1 McConnell R, Barrington-Trimis JL, Wang K, et al. Electronic-cigarette use and respiratory symptoms in adolescents. Am J Respir Crit Care Med 2016; doi:10.1164/rccm.201604-0804OC.

Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to

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