Why your nose runs

by Erik Polan, D.O., For The Inquirer

Published Feb. 27, 2016, 4:00 a.m. ET

Q: What's causing my runny nose?

A: We are approaching the time of year when cold and flu season intersect with the beginning of allergy season, and it can sometimes be hard to tell them apart. There are a few ways to differentiate between them.

In general, allergy symptoms include sneezing; a clear, watery nasal discharge; postnasal drip; or itchy eyes, nose, or throat. Seasonal allergies are most commonly caused by pollens and molds and can affect people at different times of year, depending on where they live and what they're allergic to. Continual allergies are caused by indoor factors such as pet dander, dust mites, and cockroach infestation. Both types of allergies can be treated with over-the-counter antihistamines or nasal steroid sprays.

Sinus infections - which can be caused by a virus (such as cold or flu) or bacteria - can happen at any time of year. But certain kinds, such as those caused by viruses, can occur more frequently in the winter months. Symptoms include nasal congestion with a thicker, colored nasal discharge; facial pain; sinus pressure; and possible fever. Fever is less likely with a bacterial infection.

Symptoms of a viral infection usually last seven to 10 days. Patients can use over-the-counter anti-inflammatory medication or oral or nasal decongestants to treat symptoms. Cough medicines won't cure a cough, but they can help calm it if it is particularly bothersome.

If symptoms persist and/or worsen, they are likely due to a bacterial infection. If, after 10 days, symptoms persist, the patient should notify his or her primary-care physician, as antibiotics could be necessary.

Erik Polan, D.O., is a general internist and instructor in the Department of Internal Medicine at the Philadelphia College of Osteopathic Medicine.