Singulair is a prescription medicine approved for control of asthma and seasonal allergic rhinitis (hay fever). It can safely be used by adults and children as young as 2 years old for treatment of outdoor allergies, and for children as young as 6 months old for treatment of indoor allergies. It blocks leukotrienes in the body that cause inflammation in asthma and seasonal allergic rhinitis. It is not a steroid and is generally well tolerated according to clinical studies. It comes in 10 mg tablets, 4 mg and 5 mg chewable cherry flavored tablets, or pediatric granules. Therapy is one dosage per day for 3 to 14 days. Since the dosage should be continuous, it cannot be used for an acute asthma attack.