Quick facts
| Generic name | montelukast sodium |
|---|---|
| Brand names | Singulair |
| Drug class | Leukotriene receptor antagonist |
| Generally used for | A daily tablet used to help control asthma, prevent exercise-induced airway narrowing, and relieve allergic rhinitis symptoms. |
Health Captain explains what a medicine is generally used for, how its class works, and what to discuss with your care team. We never publish dosing, and this page cannot account for your medical history, kidney or liver function, pregnancy, or the other medicines you take. This is education, not prescribing advice — follow the instructions on your label and ask your prescriber or pharmacist.
What is Montelukast?
Montelukast blocks the receptor for leukotrienes, inflammatory messengers released during allergic and asthmatic reactions that constrict airways, draw in immune cells, and increase mucus. Taken daily as a tablet, it reduces those effects. It carries an FDA boxed warning about serious neuropsychiatric events, and FDA advises reserving it for allergic rhinitis when other treatments are inadequate.
Key takeaways
- Montelukast blocks a different inflammatory pathway from antihistamines and from corticosteroids.
- It carries an FDA boxed warning about serious mental health side effects, including agitation, depression, sleep disturbance, and suicidal thoughts and behavior.
- FDA advises that for allergic rhinitis it be used only when other treatments have not worked or are not tolerated, because of that risk profile.
- It is a controller taken regularly, not a rescue medicine for an attack in progress.
- This page is general education, not prescribing advice — whether this medicine is right for you, and how it is dosed, is individualized and decided by you and your prescriber.
How it generally works
When mast cells and other immune cells are triggered — by an allergen, by exercise, sometimes by aspirin — they release leukotrienes. These messengers tighten airway smooth muscle, make blood vessels leaky so tissue swells, pull inflammatory cells into the airway, and increase mucus. They are a distinct pathway from the histamine that antihistamines block.
Montelukast occupies the receptor those leukotrienes act on, so the message does not get through. Because it is a tablet rather than an inhaler, it appeals to people who struggle with inhaler technique, and it addresses both nasal and lower airway symptoms. It is generally less effective than an inhaled corticosteroid for asthma control, so it is more often an addition than a replacement.
Common side effects
Most people tolerate Montelukast well, and many effects settle as the body adjusts. Tell your prescriber or pharmacist about anything that persists or bothers you.
- Headache
- Abdominal pain or nausea
- Upper respiratory infection symptoms reported in trials
- Cough
- Fatigue
- Fever in children
- Sleep disturbance or vivid dreams
Serious side effects
These are uncommon, but they are the ones to act on rather than wait out. Contact a clinician promptly if you notice any of them. If you believe you are experiencing a medical emergency, call emergency services immediately (911 in the United States).
- New or worsening agitation, aggression, irritability, anxiety, or depression — reported in both children and adults and covered by the boxed warning
- Suicidal thoughts or behavior — seek help immediately; in the US you can call or text 988 for the Suicide and Crisis Lifeline
- Hallucinations, disorientation, or unusual confusion
- Rash with blistering, or numbness and weakness with a rash — very rare vasculitic reactions have been reported
- Yellowing of the skin or eyes — rare liver injury
Important warnings
FDA boxed warning
A boxed warning is the strongest warning the US Food and Drug Administration applies to a medicine. It does not mean nobody should take it — it means the risk below is serious enough that it must be weighed deliberately with your prescriber.
- Serious neuropsychiatric events — montelukast carries an FDA boxed warning. Reported events include agitation, aggression, depression, sleep disturbance, hallucinations, suicidal thoughts, and completed suicide, in adults, adolescents, and children, sometimes in people with no psychiatric history.
Other warnings and precautions
- Benefit-risk in allergic rhinitis — FDA advises reserving montelukast for allergic rhinitis in patients who have an inadequate response or intolerance to alternative therapies.
- Not for acute attacks — montelukast does not relieve bronchospasm in progress and does not replace a rescue inhaler.
- Do not use it to replace an inhaled corticosteroid without a prescriber’s decision; abruptly substituting can worsen asthma control.
- Aspirin-sensitive asthma — montelukast does not remove the need to avoid aspirin and NSAIDs in people with that sensitivity.
- Phenylketonuria — some chewable formulations contain phenylalanine.
Drug interactions
Interactions are one of the most common avoidable medication problems. Keep one list of everything you take — including supplements and over-the-counter products — with the Medication List Builder, and read our guide to drug interactions.
- Strong CYP inducers such as rifampin, phenobarbital, and phenytoin — can reduce montelukast levels.
- Gemfibrozil — can raise montelukast exposure.
- Other asthma and allergy medicines — generally used together deliberately rather than interacting harmfully; the concern is substitution, not combination.
- Alcohol — may compound sleep disturbance and mood effects for some people.
- Any medicine affecting mood or sleep — worth flagging given the neuropsychiatric warning.
Monitoring
What a care team typically keeps an eye on while someone is taking Montelukast. The exact schedule is individual.
- Mood, behavior, and sleep — specifically asked about at each visit, including in children
- Asthma control measures: symptom frequency, rescue inhaler use, nighttime waking
- Nasal symptom relief if used for allergic rhinitis, with a defined point to reassess
Storage
- Store tablets at room temperature, away from moisture and light.
- Keep the oral granule packets sealed until use, following the label instructions.
- Keep out of reach of children and dispose of unused medicine through a take-back program.
Questions for your doctor or pharmacist
Pharmacists are the most under-used resource in medicine, and the conversation is usually free. Build an agenda with Appointment Prep.
- Can we go through my full medication list together — prescriptions, over-the-counter products, vitamins, herbal products, and supplements — to check for interactions, duplicates, and anything I no longer need?
- Given the boxed warning, why is this the right choice for me rather than an alternative?
- What mood, sleep, or behavior changes should I or my family watch for, and who do we call?
- Is this replacing or adding to my inhaled controller?
- How will we judge whether it is actually helping, and when will we review it?
- If I am taking it for hay fever, have we tried the other options first?
Frequently asked questions
What exactly does the montelukast boxed warning say?
FDA added a boxed warning in 2020 about serious mental health side effects — including agitation, aggression, depression, sleep disturbance, hallucinations, and suicidal thoughts and actions — reported in adults, adolescents, and children, sometimes in people with no prior psychiatric history. FDA also advised limiting use in allergic rhinitis to people who cannot use or did not respond to other treatments.
Should my child stop taking montelukast?
That is a decision for the prescriber, not something to do abruptly — stopping asthma control medication can lead to a flare. What the warning does justify is a specific conversation: is montelukast still needed, is it working, is there an alternative, and what behavior changes should the family watch for. Bring that question to the next appointment, or sooner if you have concerns.
Can montelukast replace my inhaler?
Generally not. It never replaces a rescue inhaler, and for most people with persistent asthma it is less effective than an inhaled corticosteroid as a controller. It can be a reasonable add-on, an option for exercise-induced symptoms, or a choice for someone who genuinely cannot manage inhaler devices. That judgment belongs with your clinician.
Sources
- MedlinePlus — Drugs, Herbs and Supplements — Plain-language drug information from the US National Library of Medicine; search for montelukast.
- DailyMed — montelukast labeling — The current FDA-approved prescribing information submitted by manufacturers.
- FDA — Drug Safety and Availability — Safety communications, label changes, recalls, and shortage notices.
- AAAAI — Conditions and Treatments — American Academy of Allergy, Asthma & Immunology patient information.
- NHLBI — Asthma — US National Institutes of Health asthma information.
Health Captain links to primary public-health and clinical sources so you can read the original material yourself. See our sources policy.