By blocking leukotriene receptors, the drug can prevent leukotrienes (chemicals produced by the body in response to allergens or other problems) from causing allergy or
asthma symptoms. Singulair has been shown to be safe and effective for adults and children as young as two years old (for seasonal allergies) or as young as six months old (for year-round allergies).
Although using Singulair for allergies is very common and considered relatively safe, you should tell your healthcare provider about any existing medical conditions you have before starting treatment. It is important to talk to your healthcare provider prior to using Singulair if you have phenylketonuria, liver disease, or any allergies (including allergies to food, dyes, or preservatives).
(Click Singulair for more information about specific Singulair uses, to learn more about the effects of this drug, and to find out what side effects could occur during treatment.)