Serevent (Salmeterol) is a beta receptor stimulant used to prevent or minimize problems in persons with breathing difficulties including asthma and chronic obstructive disorders of the lungs such as chronic bronchitis or emphysema. It works by opening the air passages in the lungs to improve breathing. It will not stop an asthma attack once one has started. Salmeterol is generally combined with another effective controller-type asthma medicine (such as an inhaled corticosteroid). This medicine may also be used to treat other conditions as determined by your doctor.