Catarrh (pronounce /kəˈtɑr/) is a thick exudate of mucus and white blood cells caused by the swelling of the mucous membranes in the head in response to an infection. It is a symptom usually associated with the common cold and chesty coughs, but can also be found in patients with infections of the adenoids, middle ear, sinus or tonsils. The catarrh may either discharge or cause a blockage which may become chronic.