Related symptoms Congestion almost always causes difficulty in breathing, although if the main problem is in the sinuses there is little interference with breathing but often a painful headache . Coughing frequently occurs in an effort to keep the passages to the lungs clear. Often the underlying cause of congestion is an infectious disease that results in fever or fatigue . The primary causes of congestion are allergies or asthma , bronchitis , and infectious diseases of the respiratory system, especially the common cold and pneumonias of all types. More rarely congestion is the result of nasal administration of drugs such as cocaine or a complication of syphilis .
Prevention depends on the cause of the congestion.
Allergies and asthma can be treated before congestion develops, for example, but avoiding infection is the best way to prevent colds. Although coughing is uncomfortable, it helps relieve congestion of the throat or lungs . Medicines called decongestants suppress the production of mucus, the fluid that is filling parts of the respiratory system.