Phlegm
Mucus in the Lungs: Symptoms, Diagnosis, Causes & Treatment
Mucus in the lungs is produced by the respiratory system, and can be a symptom of health conditions like pneumonia, tuberculosis, asthma, bronchiectasis or chronic obstructive pulmonary disease. Learn more about the symptoms associated with mucus in the lungs, what causes it, and how it's diagnosed and treated.