Menthol Cough Drops: Cause for Concern?

Background: Over-the-counter (OTC) cough remedies are lightly regulated and their potential side effects may go unrecognized. During 2015, over 282 million cough drops were sold in the United States. A Wisconsin community clinician (RM) made clinical observations suggesting that excessive use of OTC cough drops may exacerbate rather than benefit coughs. The goal of this project was to assess whether menthol in cough drops is related to worse cough symptoms.

Methods: From April 2016 through May 2017, 5 Wisconsin primary care clinics invited adolescent and adult outpatients seeking medical care for an acute or subacute cough to take a voluntary, anonymous, 10-question cough drop use survey that included age, sex, smoking status, cough severity, cough duration, and cough drop use (including type and amount).

Results: Of the 548 surveys collected and analyzed, 363 (66.2%) reported using cough drops. Cough drop use was significantly associated with longer duration of cough at presentation ( < .001) but not with overall cough severity ( = .09). Of cough drop users, 269 (90%) reported consuming drops with menthol. Univariate analysis found no statistically significant differences between the menthol and nonmenthol groups for either severity ( = .65) or duration ( = .17). However, significant independent associations were found between cough severity and 1) average menthol dose per cough drop (R = 0.19; = .007), 2) number of cough drops consumed daily (R = 0.2; = .002) and 3) total amount of menthol consumed per day (R = 0.21; = .001) that remained significant ( = .003) after controlling for age, sex, smoking status, season, and clinic site.

Conclusions: Cough severity in some individuals may be negatively influenced by the amount of menthol consumed via cough drops. Clinicians should include cough drop use in history taking of patients with persisting cough illnesses. Further research into potential mechanisms is warranted.