Constant phlegm in the throat may be a symptom of pneumonia, cystic fibrosis or asthma, according to Healthgrades. Excess phlegm can also be a result of smoke exposure, dairy products, certain medications and airway obstruction.
Pneumonia is a lung infection caused by bacteria, viruses or fungi, notes Healthline. The condition causes inflammation in the lungs' air sacs, which fill with fluid and make breathing difficult. Other symptoms of pneumonia include chest pain, fever, dry cough and muscle aches. Several risk factors exist for developing the condition, including a previous stroke, a weakened immune system and drug abuse.
Cystic fibrosis is a genetic disorder that affects cells that produce mucus, sweat and digestive juices, explains Healthline. The condition causes mucus to thicken and become stickier, clogging glandular secretions and leading to symptoms such as a salty taste to the skin, cough, wheezing, and other respiratory and digestive problems.
Asthma is a disease that affects the lungs, which become inflamed, according to the National Heart, Lung, and Blood Institute. When the airways of the lungs become inflamed and react to certain inhaled substances, they can tighten, leading to increased mucus production. Symptoms of asthma include periods of wheezing, shortness of breath, coughing and chest tightness. The condition can be the result of a variety of genetic and environmental factors, including atopy, parents with asthma, contact with airborne allergens in early childhood and respiratory infections during childhood.