In the acute stage of inflammation, the mucous membrane is at first dry and swollen. The catarrhal discharge is purulent, tenacious, thick and ropy or stringy. It is at first frothy, then spots of gummy pus. In color it is at first white, then yellow and finally green. In recovery, under adjustment, the discharge will become thinner and more plentiful for a time as it returns to its natural consistency.
Pathologists define catarrh as an inflammation of a mucous membrane.
The thickening mucus is a result of a membrane being inflamed. Catarrh may be acute or chronic. Catarrh of the nasal mucous membrane is known as rhinitis. Inflammation of the bronchial tubes results in bronchitis or pulmonary catarrh. Hay fever is the result of the mucous membrane of the eyes and air passages being inflamed.