UW Study: Excessive Use of Menthol Cough Drops Could Actually Increase Coughs

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It started with a Green Bay doctor's observation: his patients generally didn't mention cough-drop use when he asked about over-the-counter remedies they used.

 

Inspired by that observation, a new study of more than 500 patients has shown that too many cough drops - especially those containing menthol - may actually make coughs more severe.

 

The study was conducted by the Wisconsin Research and Education Network (WREN), headquartered in the department of family medicine and community health at the UW School of Medicine and Public Health.

 

Dr. Robert Mead, a family-medicine physician with Bellin Health, followed up his original observation by asking patients with persistent and unexplained coughs to stop using cough drops. He observed that coughs then resolved over a matter of days.

 

"Menthol is in lots of cough drops and over-the-counter drugs," said Mead. "I was astounded by the number and frequency of cough drops patients were using. Some went through an entire bag (20) in one day! I wondered if menthol was causing 'rebound' coughs."

 

Mead went to Dr. David Hahn, a senior scientist at WREN, a group that conducts primary-care research in partnership with primary-care clinicians. Hahn found Mead's theory intriguing and began a study.

 

"The limited availability of evidence indicates that side effects of over-the-counter (OTC) cough drops may not be recognized," said Hahn.

 

A 10-question survey that included age, sex, smoking, cough duration and severity, and OTC cough drop use was distributed to patients who had a cough. The patients, all over age 13, were recruited from five rural, urban and suburban primary-care clinics that are members of WREN. The study group was mostly middle-aged; two-thirds were female and the majority had never smoked.

 

Of the 548 eligible surveys, 66 percent of those responding used cough drops. Reported duration of cough illness at the time of the clinic visit was greater in cough-drop users (12.5 days) compared with non-users (9.8 days). Cough also was more severe in cough-drop users.

 

These results are not surprises because people with more prolonged severe symptoms are expected to seek out more relief, including from cough drops.

 

However, Hahn did not think that people would intentionally seek out drops with higher menthol doses, so he calculated the menthol content of cough drops patients took a day and over what period and found significant correlations between cough severity and:

  1. The number of menthol drops per day
  2. The menthol dose per cough drop, and
  3. The daily menthol dose (that sometimes exceeded 100 milligrams - equivalent to more than a bag of drops taken per day)

Hahn suggested that studies on the possible negative side effects of menthol cough drops would be a good next step. But at the very least, primary-care providers are encouraged to ask more questions about OTC cold medications.

 

"A history of OTC cough-drop use should be included in the clinical evaluation of a severe and/or persistent and unexplained cough," said Hahn.

 

The study was published in the Journal of the American Board of Family Medicine.


Date Published: 03/08/2018

News tag(s):  research

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