Singulair is a leukotriene (loo-koe-TRY-een) inhibitor. Leukotrienes are
chemicals your body releases when you breathe in an allergen (such as pollen).
These chemicals cause swelling in your lungs and tightening of the muscles
around your airways, which can result in asthma symptoms.

Singulair is used to prevent asthma attacks in adults and children as young as
12 months old. Singulair is also used to prevent exercise-induced
bronchoconstriction (narrowing of the air passages in the lungs) in adults and
children who are at least 6 years old.

Singulair is also used to treat symptoms of year-round (perennial) allergies
in adults and children who are at least 6 months old. It is also used to treat
symptoms of seasonal allergies in adults and children who are at least 2 years
old.

Singulair is used for allergies, only after other treatments have failed.

**If you already take Singulair to prevent asthma or allergy symptoms, do not
use an extra dose to treat exercise-induced bronchoconstriction.**





Get emergency medical help if you have **signs of an allergic reaction to
Singulair:** hives, blisters, severe itching; difficult breathing; swelling of
your face, lips, tongue, or throat.

Tell your doctor right away if you have signs of blood vessel inflammation:
flu-like symptoms, severe sinus pain, a skin rash, numbness or a "pins and
needles" feeling in your arms or legs.

Some people using Singulair have had new or worsening mental problems. Stop
taking this medicine and call your doctor right away if you have unusual
changes in mood or behavior, such as:

  * agitation, aggression, feeling restless or irritable;

  * anxiety, depression, confusion, problems with memory or attention;

  * stuttering, tremors, uncontrolled muscle movements;

  * suicidal thoughts or actions;

  * hallucinations, sleep problems, vivid, dreams, sleep-walking; or

  * compulsive or repetitive behaviors.

Common Singulair side effects may include:

  * stomach pain, diarrhea;

  * fever or other flu symptoms;

  * ear pain or full feeling, trouble hearing;

  * headache; or

  * cold symptoms such as runny or stuffy nose, sinus pain, cough, sore throat.

This is not a complete list of side effects and others may occur. Call your
doctor for medical advice about side effects. You may report side effects to
FDA at 1-800-FDA-1088.

Singulair side effects (more detail)