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Prevents breathing problems.

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Prescription onlyLower-cost generic available

Our bottom line

Singulair (Montelukast) has fewer side effects but doesn't work as well as steroid inhalers for asthma. It also helps with allergies.


  • Prevents symptoms and improves lung function in children and adults with chronic asthma.
  • A single 10 mg dose improves exercise-induced asthma symptoms for up to 24 hours.
  • Fewer side effects compared to other asthma treatments.
  • Also relieves nasal allergy symptoms.
  • Effective pill alternative to corticosteroid inhalers.
What do people say?
552 reviews


  • You have to use Montelukast every day to control your symptoms.
  • Somewhat less effective than corticosteroid inhalers for asthma.
  • There's no generic available, so it can be expensive.
  • Can cause behavior changes, agitation, aggression, and difficulty sleeping for some people.

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What to expect when you take Singulair (Montelukast) for Asthma

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Tips from our pharmacists
  • Take it once a day to control asthma and allergy symptoms.
  • If you're using it for asthma or allergies, take it in the evening.
  • Use it 2 hours before exercising.
  • Granules can be taken by mouth or dissolved in liquid or soft food.
  • Doesn't treat sudden wheezing or asthma attacks once they start. Keep a fast-acting (rescue) inhaler with you.
  • The chewable tablets contain aspartame, so don't use them if you have a sensitivity to phenylalanine or phenylketones.
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Side effects for Singulair (Montelukast)

From clinical trials of Singulair / Asthma: Adults > 15 yrs (10 mg/day)  ( 3135)

  • HeadacheHeadache18% for Montelukast vs.18% for placebo
  • FluFlu4% for Montelukast vs.4% for placebo
  • Pain, abdominalPain, abdominal3% for Montelukast vs.3% for placebo
  • CoughCough3% for Montelukast vs.2% for placebo
  • IndigestionIndigestion2% for Montelukast vs.1% for placebo
  • Pain, dentalPain, dental2% for Montelukast vs.1% for placebo
  • Gastroenteritis, infectiousGastroenteritis, infectious2% for Montelukast vs.0% for placebo
  • DizzinessDizziness2% for Montelukast vs.1% for placebo
  • Muscle weakness/fatiguea/fatigueMuscle weakness/fatiguea/fatigue2% for Montelukast vs.1% for placebo
  • FeverFever2% for Montelukast vs.0% for placebo

Risks and Warnings for Singulair (Montelukast)

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    • Higher risk if:
    • Exercise-induced asthma
    • Other environmental triggers

    Singulair (Montelukast) is not used to treat sudden wheezing or asthma attack. You should have a fast-acting (rescue) inhaler with you all the time especially if you are prone to asthma during exercise. Talk to you doctor if your symptoms do not improve or seem to worsen while taking Singulair (Montelukast).

Means that some groups have a high risk of experiencing this side effect

Tips from pharmacists and people taking Singulair (Montelukast)

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The FDA category for this medication is B. It is advised that you: Probably safe
  • Risks from our pharmacists
  • There are reports of liver injury in people taking Singulair (Montelukast) mostly in combination with other factors such as drugs, alcohol, and liver disease. If you have any of these risk factors, your doctor will need to check your liver function periodically.
  • Tips from our pharmacists
  • Granules can be taken by mouth or dissolved in liquid or soft food.
  • Upsides and downsides from our pharmacists
  • Can cause behavior changes, agitation, aggression, and difficulty sleeping for some people.
  • Risks from our pharmacists
  • Rare cases of behavior changes occur in adults and children taking Singulair (Montelukast). Symptoms range from irritability and memory problems to hallucinations and suicidal thinking. It is not clear if this is linked to history of these conditions. Get medical help immediately if you notice symptoms of agitation, aggression, sleep disturbance, or suicidal thoughts while taking Singulair (Montelukast).
  • I was prescribed it when I was 11/12 and while it worked amazingly for my asthma and allergies it had incredibly lasting negative effects. I had all except sleep walking. But since my personal life was bad too we didn't put the 2 together.