Drinking plenty of fluids can help decrease the thickness of phlegm and make it easier to remove. Bloody, brown, white, yellow, or green phlegm may be a sign of an underlying condition or infection.

Problems in the lungs can cause phlegm to change color. Green or yellow phlegm can occur with an infection, but brown phlegm might indicate bleeding in the lungs. Phlegm is a type of mucus that comes ...