Asthma

A form of constant inflammation of the airways, which can result in breathing difficulties, whistling or hissing in the chest, coughing or thick, sticky mucus. Asthma can be caused by an allergy to various substances, in which case it is known as allergic asthma. Asthma can also result from an infection of the airways or contact with irritants, in which case it is known as non-allergic asthma.