Q. My daughter's cough has lasted for weeks. Why won't it go away?
A. Some coughs can persist for a long time—they're usually the result of a virus that's hanging on. If it lasts more than about ten days, though, see the doctor.
Most of these viral coughs are harmless but can bother a child at inconvenient times, such as during physical play (causing coughing fits) or at night, when they interrupt sleep. The most important question to ask yourself is, How much is the cough bothering her?
If she still plays happily, sleeps well and doesn't have a fever, don't worry: The cough will go away in time. But if her quality of life is affected (specifically, she's missing play or sleep) and she runs even a low-grade fever, then she should see a doctor, who can tell whether the cough may be tied to a sinus infection or allergies.
If it's due to a sinus infection (in which mucus-y fluids trigger a postnasal drip and, consequently, a cough), your child is likely to have puffy eyes; a snotty nose; a peaked, droopy look (which I call the "sinus face"); bad breath; and general weariness. While sinus infections are almost always treated with antibiotics, I've found that flushing out the nose with over-the-counter saltwater nose drops can help too.
An allergy to dust, cigarette smoke, or a new pet can also lead to a persistent cough. If your child has symptoms such as watery eyes and a runny nose, wheezing, and constant clearing of the throat, your pediatrician may suggest a visit to a pediatric allergist, to better determine which allergens are bothering him.