This medications is commonly used to treat allergy and asthma symptoms. It is a leukotriene receptor antagonist, which works by blocking the action of leukotrienes, which are inflammatory mediators that cause symptoms such as wheezing, coughing, and shortness of breath. It is an antihistamine, which works by blocking the effects of histamine, a chemical released during an allergic reaction that causes symptoms such as itching, sneezing, and runny nose.