Go to any movie theater and you’ll hear coughing, as common as the rustling of popcorn bags. Most of us think of coughs as harmless, usually just a symptom of a cold. But “a cough is never normal,” says critical care pulmonologist Nicola Hanania, M.D., director of the Asthma Clinical Research Center at Baylor College of Medicine in Houston, Texas. Coughs always signal that something’s wrong – that excess mucous, stomach acid, smoke or even a medication (most commonly blood pressure drugs) has irritated nerves in passages leading to the lungs. The resulting cough is working to clear them.

Your sinuses are painful, but you have no signs of a respiratory infection, like achiness The cough and drip lasts more than two weeks You have to travel on an airplane