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Singulair (montelukast)

Singulair (montelukast) is a leukotriene modifier. Singulair is approved for:1

  • Long-term treatment of asthma for people ages 12 months and older.
  • Prevention of exercise-induced asthma for people ages 6 years and older.
  • Treatment of seasonal hay fever (allergic rhinitis) for people ages 2 years and older.
  • Treatment of year-round hay fever for people ages 6 months and older.

It is made by Merck & Co. Singulair is taken by mouth. It comes as tablets, chewable tablets, and oral granules.

How does Singulair work?

Singulair prevents the chemical reactions that cause airway narrowing. Inflammatory cells called mast cells and eosinophils make chemicals called leukotrienes.1 The leukotrienes send the signals that increase airway swelling and tightening. Singulair blocks the “leukotriene receptor.” This prevents the signal from getting passed along.

How is Singulair taken?

Singulair is taken by mouth. For asthma, the medication label says to take one dose in the evening.1 To prevent exercise induced asthma, the label says to take one dose of Singulair at least two hours before exercising. Your health care provider will tell you what the right dose is based on your age.

Singulair comes in several strengths:1

  • 10 mg tablets
  • 4 mg and 5 mg chewable tablets
  • 4 mg oral granules

Singulair granules can be given to children in several ways:2

  • Right in the mouth.
  • Dissolved in one teaspoon of cold or room temperature breast milk or baby formula.
  • Mixed with one spoonful of a cold or room temperature soft food (for example: applesauce, mashed carrots, rice cereal, ice cream).

Do not store any leftover foods mixed with Singulair for use at a later time.

What should I do if I miss a dose of Singulair?

If you miss a dose of Singulair, just take the next dose at the regular time.2 Do not take two doses at once.

What are the recommendations for storing Singulair?

Store Singulair at room temperature (77˚F), away from moisture and light.1

What are the possible side effects of taking Singulair?

All the leukotriene modifiers, including Singulair, can cause changes in mood or behavior.2,3

The most common side effects of Singulair are flu or flu-like symptoms, such as fever, headache, sore throat, cough, or runny nose.2 Other side effects include infection (upper respiratory, sinus, or ear), stomach pain, and diarrhea. This is not an exhaustive list of side effects.

A rare and serious side effect of Singulair is an increase in eosinophils (white blood cells) and inflamed blood vessels.2 This side effect is more likely if you have been taking oral steroids and are stopping or reducing the dose. Tell your health care provider if you get a pins and needles feeling, flu-like illness, rash, or severe sinus inflammation.

Are there people who should not take Singulair?

If you are allergic to any ingredient in Singulair, you should not take this medication.2

Tell your health care provider if you are allergic to aspirin or have phenylketonuria.2 Tell your health care provider about any prescription or over-the-counter medications or supplements that you take.

Singulair has not been well studied in pregnant or breastfeeding women.2 Little is known about whether this medication passes into breast milk. Talk to your doctor about if you become pregnant or wish to breastfeed while taking Singulair.

What evidence do we have that Singulair works in people with asthma?

Two high-quality studies compared Singulair with another asthma drug and a fake treatment (placebo).1 More than 1,500 adolescents and adults participated in these studies. People treated with Singulair had better lung function than people who got placebo. One of the studies showed that people treated with Singulair had significantly fewer asthma attacks and were less likely to need oral corticosteroids. The other study did not produce these results.

One study included 336 children ages six to 14 years. The children given Singulair had better lung function and needed less rescue medication. A study in very young children (two to five years) showed that Singulair is safe for this age group, reduces asthma symptoms, and reduces use of other asthma medications.

Additional studies have shown that Singulair is effective when used together with inhaled corticosteroids. Aspirin-sensitive patients had better asthma control when they took Singulair.

Three studies with 160 adults and adolescents and one study of 64 children evaluated Singulair for preventing exercise-induced asthma. Singulair was more protective than placebo when people exercised two hours after taking the medication. It was not as effective 8.5 and 24 hours after administration. Studies have not shown that daily administration of Singulair can prevent exercise-induced asthma symptoms.

Is there a generic alternative to Singulair?

Yes, generic montelukast is available.

Written by: Sarah O'Brien | Last Reviewed: September 2019.
  1. Singulair® [prescribing information]. Whitehouse Station, NJ: Merck & Co.; 2012.
  2. Singulair® [patient information]. Whitehouse Station, NJ: Merck & Co.; 2012.
  3. US Food and Drug Administration. FDA requests labeling change for leukotriene modifiers. Accessed 2/13/15 at: