Dulera is used to control and prevent symptoms (wheezing and shortness of breath) caused by asthma. It contains 2 medications: mometasone and formoterol. Mometasone belongs to a class of drugs known as corticosteroids. It works by reducing the irritation and swelling of the airways. Formoterol belongs to the class of drugs known as long-acting beta agonists. It works by opening airways in the lungs to make breathing easier.