Health information to help you understand symptoms. It isn't a diagnosis.
Check symptoms

Montelukast

Brand names: Singulair

Montelukast is a daily pill that helps prevent asthma symptoms and can ease allergy symptoms.

Brand namesSingulair
Type of medicineLeukotriene blocker (asthma and allergy medicine)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It blocks leukotrienes, chemicals that cause airway swelling and tightening.

It is a controller medicine. It does not stop an asthma attack that has already started.

What it's used for

  • Preventing asthma symptoms
  • Preventing exercise-related breathing problems
  • Seasonal and year-round allergies (when other medicines don't work or can't be used)

How to take it

  • Take it once a day; for asthma, usually in the evening.
  • Chewable tablets and granules are available for children.
  • Keep your rescue inhaler for sudden symptoms.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Headache
  • Stomach pain
  • Upper respiratory infection symptoms
Call 911Thoughts of suicide or harming yourself. Call or text 988 any time.
Call your provider todayNew mood or behavior changes: agitation, aggression, depression, nightmares, sleepwalking, or hallucinations
Call your provider todayPins and needles, a flu-like illness, rash, or sinus pain with swelling (rare)

Warnings

  • The FDA has a boxed warning about serious mood and behavior changes. Stop it and call your provider if they happen.
  • For allergies alone, it's usually used only when other medicines aren't right.

Other medicines, foods, and alcohol

  • Phenobarbital and rifampin can lower its effect.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Talk with your provider about the benefits and risks.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.