Leukotriene receptor antagonists are used to treat asthma, exercise-induced asthma, and allergies. These medications work by blocking leukotrienes, which are chemicals in your body that cause inflammation, swelling, and tightening of the airways. Leukotriene receptor antagonists are available in oral forms, making them easy to take. Examples include montelukast (Singulair) and zafirlukast (Accolate). You can take these medications to help control your symptoms and improve your quality of life.