Can menthol-containing cough drops worsen a cough?

Abstract

Results of an observational study published in the Journal of the American Board of Family Medicine showed that use of cough drops was associated with a longer duration of cough and worsening of cough-related symptoms compared with nonuse. Adolescent and adult patients presenting with a cough at one of five Wisconsin primary care clinics were asked to participate in an anonymous 10-item survey on cough duration and severity and OTC cough drop use. A total of 548 patient surveys were included in the analysis, of which 363 (66.2%) patients were cough drop users. For the total population, the majority were female (65.4%), had a mean age of 49.5 years, and never smoked (57.8%). Cough drop users had a significantly longer cough duration compared with nonusers (mean 12.5 d vs. 9.8 d, P < 0.0001). Sufficient information on the type of cough drops used was provided by 300 patients, of which the majority (90%) used cough drops that contained menthol. The analysis showed significant correlations between cough severity and the number of cough drops used per day, the average menthol dose per cough drop, and the total menthol dose per day. These associations remained significant even after controlling for age, sex, smoking, season, and the participating clinic site. Study researchers suggested that menthol may have adverse effects on cough in some patients. They noted that one potential mechanism is that repeated exposure to menthol may result in a rebound cough. However, they emphasized that additional data are needed to help determine the cause. A persistent cough can be due to a variety of causes, such as an infection, asthma exacerbations, untreated acid reflux, postnasal drip, or select medications (e.g., ACE inhibitor). The current data suggest that prolonged use of cough drops can also contribute to this problem. The authors wrote, “We recommend including a history of OTC cough drop use in the clinical evaluation of severe and/or persistent unexplained cough. A trial of cessation of use may be warranted in cases of excessive or prolonged menthol-containing cough drop consumption before referral for an evaluation of unexplained chronic cough.” Ask patients presenting to the pharmacy with a cough about their use of OTC products, including cough drops. Tell them that results of a new analysis suggest that use of cough drops may prolong a cough and that menthol-containing cough drops may increase cough severity. If patients have been using cough drops for an extended period, encourage them to stop to see if the cough symptoms improve. If they do not improve, refer patients to their provider to determine the cause and recommended alternative treatments.