What can be done to cure a persistent cough?

A. We all experience periods of coughing with colds, but a cough that won’t go away is not something to ignore, says James Mojica, a pulmonologist at Massachusetts General Hospital. “The lung doesn’t have pain fibers, so the way that it communicates is by generating a cough,’’ he says. In fact, irritation anywhere in the airway can trigger a cough, so the problem may originate higher up than the lungs. The best remedy is to identify and treat the underlying problem that’s triggering the coughing reflex.

Mojica says that physicians divide coughs into three stages. An acute cough brought on by a cold or other mild respiratory infection typically lasts a few days and then goes away. Any cough that lasts longer than three weeks, he says, may be on its way to becoming a chronic condition and merits a doctor’s visit. A cough that lasts eight weeks or more is considered a truly chronic cough and should be assessed.

Chronic coughs can be caused by many factors, including a persistent infection, asthma, excessive mucus in the nasal passages (called postnasal drip), inflammation of the sinuses, or heartburn from stomach acid reflux. Some coughs are caused by medications, or exposure to allergens or irritants. Smoking is also a common cause, but Mojica points out that smokers who are quitting can paradoxically experience more severe coughing as their airway starts functioning better and clearing mucus from the respiratory tract.

In rare cases, an intractable cough can be a sign of a more serious disease, including lung cancer. Because its triggers are so varied, Mojica says, it’s important to see a doctor to determine the root cause of a chronic cough. Treatments will depend on the problem, and often include over-the-counter medications like antacids for heartburn, nasal sprays for postnatal drip, or an inhaler for asthma.

Some medications directly suppress coughs by blocking the signal the brain receives that triggers a cough. Prescription medications include opiates like codeine and hydrocodone, which should be taken with caution. These medications, as well as the prescription anesthetic benzonatate, can alleviate acute coughs and keep coughs from interrupting sleep at night, but they’re not a long-term solution and don’t address the underlying cause. Over-the-counter cough suppressants work in a similar way but Mojica says there’s limited evidence for their effectiveness.