Cough Drops A Culprit Behind Persistent Coughing

The phrase “too much of a good thing” may apply to cough drops. A University of Wisconsin-Madison study prompted by a Green Bay doctor shows excessive use of them could make a cough linger.

It seems counterintuitive — cough drops are supposed to make a cough better, not worse. But the Wisconsin Research & Education Network, WREN, decided to look into it after Green Bay-based family physician Robert Mead noticed patients with persistent, unexplained coughs actually got better when they stopped using cough drops.

“At the beginning of course I was a little bit dumbfounded,” said WREN Director David Hahn. WREN is part of the UW School of Medicine and Public Health.

“But my job is to try to cut off skepticism and listen to clinicians and their experiences. Because sometimes they have these counterintuitive observations that turn out to have profound impact on patient health. And this may be an example of that,” Hahn said.

The suspected culprit in cough drops? Menthol.

Mead said researchers couldn’t find any past studies about repeated or high dose exposure of menthol in cough drops. So WREN surveyed 548 patients at five primary clinics around the state. Those using cough drops had illnesses lasting 12.5 days. Those who didn’t use cough drops got better after 9.8 days.

Mead said the cross-sectional study can’t prove causation, but that primary care doctors may want to ask patients with persistent coughs about over-the-counter cold medication they’re taking. Mead, the Green Bay doctor, had noticed few of his patients bothered to mention cough drops when asked about medication even though some were using a bag of cough drops a day.

The recommendation from the study is for more research on the possible negative effects of menthol cough drops.

“Judicious use of cough drops whether they contain menthol or not can help with coughs and sore throats,” said Hahn. “And in fact even cough drops without menthol that have sugar in them can be a cough suppressant. There’s just as much evidence that sugar suppresses coughs as there is for menthol.”

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