Does inhaling menthol affect nasal patency or cough?
OBJECTIVE
There is widespread use of menthol in over-the-counter medications, despite scant information on any beneficial effects. Our aim was to assess the effect of menthol on nasal air flow, perception of nasal patency and cough challenge testing.


METHODS
Subjects comprised 42 healthy children aged 10 and 11 in a school setting. We used a single-blind pseudo-randomized cross-over trial to compare the effect of an inhalation of either menthol or placebo(eucalyptus oil). Baseline and post-intervention measurements were made on each of 2 consecutive days. Main outcome measures were (i) nasal expiratory and inspiratory flows and volumes, measured by spirometer, (ii) perception of nasal patency, assessed with a visual analogue scale (VAS), and (iii) the number of coughs in response to nebulized citric acid.


RESULTS
There was no effect of menthol on any of the spirometric measurements. Following menthol, there was a significant increase in the perception of nasal patency (mean difference in log VAS (menthol-placebo) = -0.207, 95%CI -0.329, -0.085). The cough count after menthol inhalation was reduced when compared to baseline but the change was not different from that after placebo (mean difference in cough count (menthol-placebo) = -1.71, 95%CI -4.11, 0.69).


CONCLUSIONS
Menthol has no effect on objective measures of flow but significantly increases the perception of nasal patency. It may not be possible to extrapolate these findings to younger children and those with rhinitis. Extending the study of menthol to these groups, including investigations of the efficacy and safety profiles, will provide further valuable evidence for its common use.
Kenia
Priti
P
Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
Houghton
Tom
T
Beardsmore
Caroline
C
D000280:Administration, Inhalation; D000996:Antitussive Agents / Q000627:therapeutic use*; D001985:Bronchial Provocation Tests; D002648:Child; D019343:Citric Acid; D003371:Cough / Q000188:drug therapy*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008610:Menthol / Q000627:therapeutic use*; D014663:Nasal Decongestants / Q000627:therapeutic use*; D015508:Nasal Obstruction / Q000175:diagnosis / Q000188:drug therapy*; D013147:Spirometry
D000996:Antitussive Agents; D014663:Nasal Decongestants; D008610:Menthol; D019343:Citric Acid