Skip to Content

Montelukast

Generic Name: montelukast (mon te LOO kast)
Brand Name: Singulair

Medically reviewed by Drugs.com on Jul 6, 2020 – Written by Cerner Multum

What is montelukast?

Montelukast 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.

Montelukast is used to prevent asthma attacks in adults and children as young as 12 months old. Montelukast 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.

Montelukast 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.

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

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

Montelukast may also be used for purposes not listed in this medication guide.

Important Information

Some people using montelukast have had new or worsening mental problems. Stop taking montelukast and call your doctor right away if you have any unusual changes in mood or behavior (such as anger, aggression, confusion, sleep problems, compulsive behaviors, hallucinations, or suicidal thoughts or actions).

Before taking this medicine

You should not use montelukast if you are allergic to it.

Tell your doctor if you have ever had:

  • mental illness or psychosis; or

  • asthma, or a history of severe allergic reaction (sneezing, runny or stuffy nose, wheezing, shortness of breath) after taking aspirin or another NSAID.

The chewable tablet may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

Tell your doctor if you are pregnant or breastfeeding.

Do not give montelukast to a child without a doctor's advice.

How should I take montelukast?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Montelukast is usually taken once daily in the evening for prevention of asthma or allergy symptoms. For exercise-induced bronchoconstriction, take a single dose at least 2 hours before you exercise, and do not take another dose for at least 24 hours. Follow your doctor's instructions.

Montelukast is not a rescue medicine for asthma or bronchospasm attacks. Use only fast-acting inhalation medicine for an attack. Seek medical attention if your breathing problems get worse quickly, or if you think your medications are not working as well.

Swallow the regular tablet whole, with a glass of water.

You must chew the chewable tablet before you swallow it.

The oral granules can be placed directly into the mouth and swallowed, or mixed with a spoonful of applesauce, mashed carrots, rice, or ice cream. Oral granules can also be mixed with 1 teaspoon of baby formula or breast milk. Do not use any other type of liquid for mixing the granules.

After opening or mixing the oral granules, you must use them within 15 minutes. Do not save an open packet or mixed medicine for later use.

It may take up to several weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.

Use all asthma medications as directed. Your dose needs may change due to surgery, illness, stress, or a recent asthma attack. Do not change your dose or dosing schedule without your doctor's advice. Tell your doctor if any of your medicines seem to stop working.

If you also use an oral steroid medication, you should not stop using it suddenly. Follow your doctor's instructions about tapering your dose.

Store at room temperature away from moisture and heat. Do not open a packet of oral granules until you are ready to use the medicine.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking montelukast?

Avoid situations or activities that may trigger an asthma attack.

If your asthma symptoms get worse when you take aspirin, avoid taking aspirin or other NSAIDs (nonsteroidal anti-inflammatory drugs) while you are taking montelukast. NSAIDs include ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.

Montelukast side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Tell your doctor right away if you have signs of blood vessel inflammation: flu-like symptoms, feeling weak or tired, skin rash, tingling or numbness in your arms or legs, severe sinus pain.

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

  • anger, aggression, feeling restless or irritable;

  • agitation, anxiety, depression, confusion, problems with memory or attention;

  • suicidal thoughts or actions;

  • hallucinations, sleep problems, strange dreams, sleep-walking; or

  • compulsive or repetitive behaviors.

Common 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.

What other drugs will affect montelukast?

Other drugs may affect montelukast, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.