Novel treatments for unexplained persistent coughing

Novel treatments for unexplained persistent coughing

The Medicine Cabinet: Ask the Harvard Experts

Q: I cannot get rid of this cough. I don’t smoke. My lung tests and chest X-ray are normal. I tried inhalers, acid blockers and nasal decongestants without any improvement. What else can I do?

A: Based on your question, your doctor has considered the most common causes of a persistent cough: reactive airways disease such as asthma, post nasal drip and acid reflux.

A less common condition that can cause a persistent cough is nonasthmatic eosinophilic bronchitis. The diagnosis is made by looking at a sputum sample under the microscope. It shows a lot of white blood cells called eosinophils.

You mention that you have tried inhalers. I suspect that one of them contained a corticosteroid. If not, that is something you should consider as a treatment for eosinophilic bronchitis.

Some medicines can cause a constant throat tickle and cough. It’s a common side effect of the blood pressure drugs known as ACE inhibitors like lisinopril and enalapril.

Most likely you have what doctors now call “unexplained chronic cough” — the term used to describe the 5 percent to 10 percent of people with no specific reason found for their ailment.

In the January 2016 journal Chest, a panel of experts published recommendations on the treatment of unexplained chronic cough. The experts reviewed prior medical studies to look for evidence-based therapies. They found two. One is a drug called gabapentin. The other is speech therapy.

Gabapentin was originally developed as an anti-seizure drug. However, now it is used primarily to help treat chronic pain, especially nerve pain. It’s not known how gabapentin helps decrease coughing. Most likely it acts by calming nerves that trigger coughing in some people.

The main side effect of gabapentin is sleepiness. So the drug should be started at a low dose at night and increased gradually.

If you wish to pursue speech therapy, be sure the person has experience in treating chronic cough.

(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit