What is postnasal drip? Normal sinus mucosa produces about 1 quart (about 946 ml) of mucus per day. Usually you swallow this mucus and don’t notice it. However, allergies, irritation, viruses, fungus or sinusitis can cause the mucous membranes of the nose and sinuses to swell and produce more mucus than normal. This mucus can irritate the throat and cause coughing. The sensation of excess mucus in the back of the throat is known as postnasal drip. How to diagnose and treat cough caused by postnasal drip? To diagnose the cause of postnasal drip, your doctor will ask you to have a CT scan of your sinuses or a special camera to examine your nose or throat. The goal of treatment is to stop the postnasal drip. To control postnasal drip: 1. Do not expose yourself to factors that you know may cause symptoms. These may include pollen, mold, animal dander, dust, smoke, temperature changes, and dry air; 2. Drink six to eight 8-ounce glasses (227 ml) of caffeine-free beverages a day, unless your doctor tells you otherwise. Most people don’t drink enough fluids and their mucus becomes thicker as a result. Drinking more fluids can reduce the consistency of mucus. Caffeinated beverages can increase the consistency of mucus. You may be asked to try taking some medications for a few weeks to find out if they work. This may be called a trial treatment. Ask your doctor about how long the trial treatment will last. Trial treatment may be one of many treatments to try until your chronic cough is under control. Medications prescribed by your doctor may include: 1. glucocorticoid-based nasal sprays that reduce inflammation and relieve postnasal drip; 2. antihistamines taken to reduce nasal itching, runny nose, and sneezing; 3. anticholinergic nasal sprays that help stop mucus production; 4. decongestants that are effective for nasal congestion or runny nose, sneezing, and sinus congestion; and 5. mucolytics that can be used to dissolve thick mucus. All medications may have side effects and risks. If you have any questions about the medications used or this material, please contact your doctor.