Coughing up phlegm, also known as mucus or sputum, is the result of many conditions affecting the lungs. After the nose or mouth, air is inhaled into the trachea, or windpipe, which extends from the back of the throat through the neck and into the chest. There it divides into a tube on the left and a tube on the right to each lung. The tubes then divide again and again to different segments of the lungs. These tubes have special glands in them that make mucus to help trap debris. Some short-term or long-term conditions cause these glands to multiply or be more active and produce more mucus.
COPD
According to the National Heart Lung and Blood Institute, chronic obstructive pulmonary disease, or COPD, is a lung disease that includes both emphysema and bronchitis. Emphysema is the destruction of normal lung tissue, leaving empty spaces in the lungs where functional lung tissue used to be. The result is less tissue to take oxygen into the blood. Bronchitis is long-term overgrowth of the glands that make mucus in the tubes of the lungs as well as a narrowing of airways. COPD, especially when bronchitis is the predominant type, can cause significant mucus production.
Asthma
In asthma, the airways and lungs have an exaggerated response to noxious environmental factors, including cold air. According to the National Institutes of Health, the tubes of the lungs quickly constrict, and large amounts of mucus can be produced. This results in difficulty moving air. Some types of asthma are more predominant at night.
Congestive Heart Failure
Heart conditions such as congestive heart failure can cause a wet cough in the morning. The American Heart Association notes that in this condition, the heart has trouble moving a higher than usual blood volume through the body, and fluid can back up into the tissues, including the lungs. In an upright position, more fluid backs up into the legs, and at night when a person is lying flat, more fluid backs up into the lungs. This can lead to shortness of breath and a wet cough at night or in the morning.
Pneumonia
Many different lung and airway infections can cause sputum production. They will typically, but not necessarily, be associated with a fever. Viral, bacterial and fungal sources may all be the cause of pneumonia, according to the Mayo Clinic. Aspiration, or the inhalation of food particles or fluids into the airway and lungs, also can cause pneumonia with sputum production.
