Medical News Today: What causes black mucus?

Black mucus or phlegm is usually a sign of an underlying condition, smoking, or exposure to pollutants. It may clear up on its own, but it sometimes requires treatment. Here, find out what causes black mucus and how to treat it.

Source: Health News from Medical News Today - May 8, 2019 Category: Consumer Health News Tags: Ear, Nose and Throat Source Type: news