From the FDA-approved label
Singulair
montelukast sodium · 10 mg tablet, film coated · oral
A once-daily tablet used to help prevent asthma symptoms, prevent exercise-triggered breathing problems, and relieve allergy symptoms.
- This medication has an FDA boxed warning, the FDA's most serious warning. It is about serious changes in mood, thinking, or behavior.
- It is taken to prevent symptoms over time. It is not a rescue inhaler and does not work quickly to open the airways during an attack.
- For allergy symptoms, the label says to use it only when other treatments have not worked or cannot be taken.
- Strength
- 10 mg
- Form
- tablet, film coated
- Route
- oral
- FDA application
- NDA020829
What this page covers
This page is only about the 10 mg tablet. That is the strength for adults and for people aged 15 and older. This medicine also comes in other forms, such as chewable tablets and granules. Those are different and are taken differently. Do not use this page for those.
FDA Boxed Warning
FDA Boxed Warning: serious mental-health and behavior changes
This medication carries a boxed warning, the FDA's most serious type of warning, about serious neuropsychiatric events, meaning changes in mood, thinking, or behavior.
The label lists reported events including agitation, aggression, depression, sleep disturbances, and suicidal thoughts and behavior, including suicide.
The FDA label states that because of this risk, the benefits may not outweigh the risks for some people, particularly when symptoms are mild and could be treated with other options.
If you or someone taking this medication notices changes in behavior, new mental-health symptoms, or suicidal thoughts, the label directs patients to stop the medication and contact a healthcare provider immediately.
More detail
The label states that the mechanisms behind these events are not currently well understood.
For allergic rhinitis specifically, the label instructs prescribers to reserve this medication for people who have not responded to, or cannot tolerate, alternative therapies.
Sources (4)
BOXED WARNINGBoxed Warning
“Serious neuropsychiatric (NP) events have been reported with the use of SINGULAIR.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
BOXED WARNINGBoxed Warning
“included, but were not limited to, agitation, aggression, depression, sleep disturbances, suicidal thoughts and behavior (including suicide)”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
BOXED WARNINGBoxed Warning
“Because of the risk of NP events, the benefits of SINGULAIR may not outweigh the risks in some patients, particularly when the symptoms of disease may be mild and adequately treated with alternative therapies.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
BOXED WARNINGBoxed Warning
“The mechanisms underlying NP events associated with SINGULAIR use are currently not well understood”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
What is this medication?
Montelukast, sold under the brand name Singulair, is a leukotriene receptor antagonist. It is taken by mouth as a tablet.
Leukotrienes are substances released by cells in your body that contribute to airway swelling, tightening of airway muscles, and allergy symptoms. This medication blocks a receptor those substances act on.
It is a long-term control medication. It is not a rescue inhaler and does not work quickly to open the airways during an attack.
More detail
The 10 mg tablet is described in the label as a beige, rounded square-shaped, film-coated tablet marked MSD 117 on one side and SINGULAIR on the other.
Sources (3)
1Indications and Usage
“SINGULAIR is a leukotriene receptor antagonist indicated for”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
12.1Mechanism of Action
“In asthma, leukotriene-mediated effects include airway edema, smooth muscle contraction, and altered cellular activity associated with the inflammatory process.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
3Dosage Forms and Strengths
“Tablets: 10 mg, beige, rounded square-shaped, film-coated tablets, with code MSD 117 on one side and SINGULAIR on the other.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
What is it approved to treat?
Asthma: to help prevent and manage asthma over time, in people 12 months of age and older.
Exercise-induced bronchoconstriction (EIB): to help prevent breathing problems brought on by exercise, in people 6 years of age and older.
Allergic rhinitis: to relieve symptoms of seasonal allergies (age 2 and older) and year-round allergies (age 6 months and older).
For allergy symptoms, the label says to reserve this medication for people who have an inadequate response to, or cannot tolerate, other treatments.
More detail
These approved age ranges apply to the medication across all of its forms. The 10 mg tablet covered by this page is the strength the label specifies for people 15 years and older; younger patients use the chewable tablets or oral granules.
Sources (5)
1Indications and Usage
“Prophylaxis and chronic treatment of asthma in patients 12 months of age and older”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
1Indications and Usage
“Acute prevention of exercise-induced bronchoconstriction (EIB) in patients 6 years of age and older”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
1Indications and Usage
“seasonal allergic rhinitis (SAR) in patients 2 years of age and older, and perennial allergic rhinitis (PAR) in patients 6 months of age and older”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
1Indications and Usage
“reserve use for patients who have an inadequate response or intolerance to alternative therapies”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“15 years and older: one 10-mg tablet”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Important limitations: what it does not do
This medication is not indicated to treat an acute asthma attack. It is not a substitute for a rescue inhaler.
The label instructs that people taking it should have appropriate rescue medication available.
It should not be abruptly substituted for inhaled or oral corticosteroids.
People with known aspirin sensitivity should continue to avoid aspirin and NSAIDs while taking it.
Sources (4)
1Indications and Usage
“SINGULAIR is not indicated for the treatment of an acute asthma attack.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“Advise patients to have appropriate rescue medication available”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“Do not abruptly substitute SINGULAIR for inhaled or oral corticosteroids”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“Patients with known aspirin sensitivity should continue to avoid aspirin or non-steroidal anti-inflammatory agents while taking SINGULAIR”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Common side effects
The label lists these as the most common adverse reactions reported at 5% or more, and more often than with placebo: upper respiratory infection, fever, headache, sore throat, cough, abdominal pain, diarrhea, ear infection, influenza, runny nose, sinusitis, and ear inflammation.
An important caveat from the label itself: rates seen in clinical trials cannot be directly compared with rates from other drugs' trials, and may not reflect what happens in everyday practice.
More detail
Being listed as an adverse reaction does not by itself establish that the medication caused it. For example, in the adult and adolescent asthma trials the label reports headache in 18.4% of people taking the medication and 18.1% of people taking placebo: a difference far smaller than the raw number alone suggests.
This page does not list every reported side effect. The full label and Medication Guide, linked below, contain the complete list.
Sources (3)
6Adverse Reactions
“upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, diarrhea, otitis media, influenza, rhinorrhea, sinusitis, otitis”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
6Adverse Reactions
“Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
6Adverse Reactions
“Headache Dizziness 18.4 1.9 18.1 1.4”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Serious risks to understand
Mental-health and behavior changes. See the boxed warning above. This is the most serious identified risk. The label reports these events in adults, adolescents, and children, both in people who had a previous psychiatric history and people who did not.
The label states it is difficult to identify who is at risk, or to quantify how large the risk is.
Systemic eosinophilia, sometimes with features of vasculitis consistent with Churg-Strauss syndrome, has been reported. The label notes these events have sometimes been associated with reducing oral corticosteroid therapy.
More detail
The label notes that in many cases symptoms resolved after stopping the medication, but that in some cases symptoms persisted after it was discontinued.
Sources (4)
5Warnings and Precautions
“NP events have been reported in adult, adolescent, and pediatric patients with and without a previous history of psychiatric disorder.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“it is difficult to identify risk factors for or quantify the risk of NP events with SINGULAIR use”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“Systemic eosinophilia, sometimes presenting with clinical features of vasculitis consistent with Churg-Strauss syndrome, has been reported.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
5Warnings and Precautions
“In many cases, symptoms resolved after stopping SINGULAIR therapy; however, in some cases symptoms persisted after discontinuation of”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Who should not take it, and drug interactions
The label lists one contraindication: hypersensitivity to any component of the medication.
For drug interactions, the label states that no dose adjustment is needed when it is taken with a list of common medications including theophylline, prednisone, oral contraceptives, digoxin, warfarin, and others.
This does not mean no interaction is possible with any medication. Your pharmacist can check your specific medication list.
Sources (2)
4Contraindications
“SINGULAIR is contraindicated in patients with hypersensitivity to any of its components.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
7Drug Interactions
“No dose adjustment is needed when SINGULAIR is co-administered with theophylline, prednisone, prednisolone, oral contraceptives, fexofenadine, digoxin, warfarin, gemfibrozil, itraconazole, thyroid hormones, sedative hypnotics, non-steroidal anti-inflammatory agents, benzodiazepines, decongestants, and Cytochrome P450 (CYP) enzyme inducers”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Pregnancy, children, and older adults
Pregnancy: the label states that available data from published studies over decades have not established a drug-associated risk of major birth defects. It also notes that all pregnancies carry a background risk, and that poorly controlled asthma carries its own risks.
Children: safety and effectiveness for asthma have been established in children 6 to 14 years of age, with safety and efficacy data similar to adults. Children in that age range use a different strength than the 10 mg tablet.
Older adults: the label states no dosage adjustment in the elderly is required, while noting that greater sensitivity in some older individuals cannot be ruled out.
Sources (5)
8.1Pregnancy
“Available data from published prospective and retrospective cohort studies over decades with montelukast use in pregnant women have not established a drug-associated risk of major birth defects”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
8.1Pregnancy
“All pregnancies have a background risk of birth defect, loss, or other adverse outcomes.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
8.4Pediatric Use
“Safety and effectiveness of SINGULAIR for asthma have been established in pediatric patients 6 to 14 years of age.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
8.5Geriatric Use
“No dosage adjustment in the elderly is required.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
8.5Geriatric Use
“greater sensitivity of some older individuals cannot be ruled out”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
How it is taken (as described in the label)
For asthma, the label describes once-daily dosing in the evening, with or without food.
For preventing exercise-induced breathing problems, the label describes one tablet at least 2 hours before exercise.
People who have both asthma and allergic rhinitis are directed to take only one dose daily, in the evening.
This is what the label says in general. It is not a dosing instruction for you. Follow the directions on your own prescription and ask your prescriber or pharmacist about your situation.
More detail
Which product a person takes depends on age, and the label maps them explicitly: 15 years and older take one 10 mg tablet, the product this page describes. People aged 6 to 14 take one 5 mg chewable tablet. Ages 2 to 5 take one 4 mg chewable tablet or a packet of 4 mg oral granules. Ages 6 to 23 months take a packet of 4 mg oral granules.
This matters because the strengths are not interchangeable. A 10 mg tablet is not a child's dose, and the chewable tablets and granules are separate products with their own packaging and instructions.
Sources (7)
2Dosage and Administration
“For asthma, administer SINGULAIR orally once daily in the evening, with or without food.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“One tablet at least 2 hours before exercise for patients 6 years of age and older”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“Patients with both asthma and allergic rhinitis should take only one dose daily in the evening”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“15 years and older: one 10-mg tablet”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“6 to 14 years: one 5-mg chewable tablet”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“2 to 5 years: one 4-mg chewable tablet or one packet of 4-mg oral granules”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
2Dosage and Administration
“6 to 23 months: one packet of 4-mg oral granules”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed
Reporting a side effect
The label directs suspected adverse reactions to be reported to the manufacturer at 1-844-674-3200, or to the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Reporting side effects is how safety signals like the boxed warning on this medication get identified in the first place.
Sources (1)
6Adverse Reactions
“To report SUSPECTED ADVERSE REACTIONS, contact Organon LLC, a subsidiary of Organon & Co., Inc., at 1-844-674-3200 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.”
From the FDA-approved label for SINGULAIR, version 5, effective 2025-04-30. Read this section on DailyMed