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 from the lungs and respiratory tract. Typically, phlegm is clear, thin, and unnoticeable. When someone has a cold or...
Phlegm is a type of mucus that is produced in the lungs and nearby lower respiratory tract airways. This kind of mucus has a crucial role in preventing germs and materials from entering the airways and lungs and potentially causing an infection. Other areas of the body, including the upper respiratory tract (nose, mouth, and...
