Montelukast sodium (Singulair®) is a prescription drug approved for treating asthma and allergic rhinitis. It belongs to a class of drugs called leukotriene modifiers, which work by blocking leukotriene receptors (chemicals that cause allergy or asthma symptoms).
The medication comes in several different forms, including tablets, chewable tablets, and oral granules. It is typically taken once a day, but some people only need to take it before exercising (for exercise-induced asthma).
Even though most people tolerate montelukast sodium well, side effects are possible. Some of the most common side effects that have been reported with this drug include abdominal pain, headaches, and the flu.
(Click Montelukast for more information on how montelukast sodium works, when and how to take this drug, and what you should be aware of before starting treatment.)