What causes coughing up green phglem?

Hello. Thank you for posting.

A cough is a common cold symptom. It's the body's way of getting rid of phlegm or mucus. But if a cough persists long after the cold is gone, contact your doctor.  If you are coughing up thick green or yellow phlegm, or if you are wheezing, running a fever higher than 101 F, having night sweats, or coughing up blood, you need to see a doctor. These may be signs of a more serious illness that needs to be diagnosed and treated.

Helena