E-Cigarettes Inhibit Cough Reflex Sensitivity

Electronic cigarettes comprise a nearly $3 billion market in the United States. In 2014 alone, roughly 12.6% of the US adult population admitted to smoking an e-cigarette.

Research on the physiologic effects of these increasingly popular devices is ongoing. Recently, researchers evaluated the effect that a single e-cigarette had on cough sensitivity.

The findings of this study, which appeared ahead-of-print in the January 2016 issue of Chest, suggested that a single session of e-cigarette use could diminish cough reflex sensitivity and the urge-to-cough threshold.

Seventeen healthy nonsmokers participated in a capsaicin cough challenge to measure cough reflex sensitivity at baseline, after 15 minutes, and following 24 hours from the e-cigarette exposure. Participants inhaled an e-cigarette, taking 1 puff every 30 seconds for a total of 30 puffs, which is similar to smokers’ puffing habits with tobacco cigarettes.

A subgroup of 8 participants was exposed to e-cigarettes without nicotine.

The study authors found that exposure to a single e-cigarette repressed urge-to-cough or the irritating sensation felt prior to coughing. The non-nicotine subgroup experienced no cough suppression.

Cough reflex sensitivity was transiently inhibited after 15 minutes and returned to baseline after 24 hours. The nicotine-containing e-cigarettes induced more coughing than the e-cigarettes without nicotine.

These findings supported previous hypotheses that nicotine is the agent responsible for cough suppression and has a dual mechanism of action. The researchers believed that nicotine has an immediate peripheral protussive effect and a delayed central antitussive effect.

Further studies are needed to investigate the physiologic effects of chronic e-cigarette usage. E-cigarettes’ benefits and risks remain controversial, and data are inconclusive at this time.