Montelukast (Singulair) is a leukotriene receptor antagonist used for once-daily maintenance treatment of asthma (ages 12 months and older), prevention of exercise-induced bronchoconstriction, and relief of seasonal and perennial allergic rhinitis. It works by blocking CysLT1 receptors, preventing cysteinyl leukotrienes from triggering bronchoconstriction, mucus hypersecretion, and eosinophilic airway inflammation. Common side effects include headache and abdominal pain. It carries a 2020 FDA black box warning for serious neuropsychiatric events — including aggression, depression, sleep disturbances, and suicidal thinking — particularly in children; for allergic rhinitis it is generally reserved for cases where other therapies have failed.
Montelukast
Uses & FDA Indications
Montelukast is a leukotriene receptor antagonist (LTRA) used primarily in the management of asthma and allergic rhinitis. It is taken once daily and is notable for being an oral controller medication — unlike most asthma maintenance drugs, it does not require inhalation technique.
Asthma (Maintenance)
Montelukast is FDA-approved for prophylaxis and chronic treatment of asthma in adults and children as young as 12 months. It is not a rescue medication and does not treat acute bronchospasm. It is used as an add-on to inhaled corticosteroids or, in mild asthma, as monotherapy when inhaled steroids cannot be used or are refused. Clinical guidelines generally position it as a step-up option below inhaled corticosteroids in efficacy.
Exercise-Induced Bronchoconstriction Prevention
Montelukast is approved for prevention of exercise-induced bronchoconstriction in patients 6 years of age and older. Unlike albuterol (used acutely before exercise), montelukast works through a different mechanism and provides sustained preventive coverage with once-daily use.
Seasonal and Perennial Allergic Rhinitis
Montelukast is FDA-approved for relief of symptoms of seasonal allergic rhinitis (hay fever) in adults and children 2 years and older, and perennial allergic rhinitis in adults and children 6 months and older. However, clinical guidelines generally prefer intranasal corticosteroids and antihistamines as first-line therapy for allergic rhinitis due to superior symptom control.
How It Works
Leukotrienes are potent inflammatory lipid mediators produced from arachidonic acid via the 5-lipoxygenase pathway. They are released by mast cells, eosinophils, and basophils in response to allergen exposure and inflammatory stimuli. The cysteinyl leukotrienes (LTC4, LTD4, LTE4) are among the most potent bronchoconstrictors known — thousands of times more potent than histamine on a molar basis — and also promote mucus secretion, airway edema, and recruitment of eosinophils.
Montelukast selectively and competitively blocks cysteinyl leukotriene type 1 (CysLT1) receptors on airway smooth muscle cells and other inflammatory cells. By preventing leukotriene binding, it reduces bronchoconstriction, decreases mucus production, diminishes airway edema, and attenuates eosinophilic inflammation — addressing multiple components of the asthmatic response with a single daily oral tablet.
Montelukast is particularly effective in "aspirin-exacerbated respiratory disease" (AERD) — a syndrome of asthma, nasal polyps, and sensitivity to aspirin and NSAIDs. In AERD, NSAIDs shunt arachidonic acid metabolism toward leukotriene production. Blocking leukotriene receptors provides meaningful symptom relief in this challenging population.
For allergic rhinitis, leukotriene receptor blockade reduces nasal congestion, sneezing, and rhinorrhea — symptoms that are partly leukotriene-mediated. Montelukast is particularly useful when both asthma and allergic rhinitis coexist ("the unified airway"), allowing treatment of both conditions with a single agent.
Side Effects
Common
- Headache (most common)
- Abdominal pain, dyspepsia, nausea
- Fatigue
- Elevated liver enzymes (rare with standard use)
- Upper respiratory tract infection symptoms
Neuropsychiatric Effects (Black Box Warning)
- Agitation, aggression, hostility
- Anxiety, depression
- Abnormal dreams, insomnia, somnambulism (sleepwalking)
- Tremor, memory impairment
- Suicidal thinking and behavior (rare but reported)
- OCD-like symptoms, hallucinations (rare)
Rare
- Eosinophilic granulomatosis with polyangiitis (EGPA/Churg-Strauss syndrome) — reported when oral steroids are tapered; may unmask underlying condition rather than cause it
- Hypersensitivity reactions including anaphylaxis, angioedema, urticaria
Drug Interactions
| Drug / Class | Interaction | Clinical Significance |
|---|---|---|
| Rifampin (rifampicin) | Potent CYP3A4/CYP2C8 inducer reduces montelukast plasma levels by approximately 40%; may reduce therapeutic efficacy | Moderate — monitor asthma control; dose adjustment may be needed |
| Phenobarbital / phenytoin | Enzyme inducers increase montelukast metabolism, potentially reducing efficacy | Moderate — monitor clinical response to montelukast |
| Gemfibrozil | Inhibits CYP2C8 (a minor montelukast metabolic pathway), modestly increasing montelukast exposure | Low — generally well-tolerated; monitor neuropsychiatric symptoms |
| CYP3A4 inhibitors (e.g., itraconazole, clarithromycin) | May increase montelukast plasma concentrations | Low — clinical significance generally modest; monitor for side effects |
| Aspirin / NSAIDs (in aspirin-sensitive asthma) | Not a pharmacokinetic interaction; aspirin/NSAIDs trigger leukotriene overproduction that montelukast partially blocks. Montelukast does not provide complete protection | Clinical note — aspirin and NSAIDs should still be avoided in AERD; montelukast is an adjunctive measure only |
Warnings & Contraindications
⚠ BLACK BOX WARNING (added 2020): Montelukast can cause serious neuropsychiatric events including agitation, aggressive behavior, anxiety, depression, disorientation, dream abnormalities, hallucinations, insomnia, irritability, memory impairment, obsessive-compulsive symptoms, restlessness, somnambulism, suicidal thinking and behavior, and tremor. These events have been reported in patients of all ages with and without psychiatric history. Because the benefits of montelukast for allergic rhinitis may not outweigh these risks, montelukast is generally reserved for patients who have an inadequate response or intolerance to alternative therapies for this indication.
Not a Rescue Medication
Montelukast is a controller/preventive medication. It has no role in treating acute asthma attacks or acute bronchospasm. Patients must continue to carry and use a short-acting bronchodilator (such as albuterol) for acute symptoms. Montelukast should not be substituted for inhaled corticosteroids without medical guidance.
Phenylketonuria (PKU)
The chewable tablet formulation contains phenylalanine (from aspartame). Patients with phenylketonuria (PKU) should use the standard tablet or oral granule formulations instead.
Aspirin and NSAID Sensitivity
Patients with known aspirin sensitivity should continue to avoid aspirin and NSAIDs even while taking montelukast. The drug reduces but does not eliminate the leukotriene-mediated component of aspirin-exacerbated reactions.
Frequently Asked Questions
Why is montelukast taken at night?
Clinical studies showed that evening administration of montelukast results in slightly better asthma control than morning dosing, particularly for overnight and early-morning symptoms — the time when asthma is most problematic for many patients. Airway inflammation and leukotriene levels tend to peak in the early morning hours, and evening dosing aligns peak drug activity with this vulnerable window. There is no strict requirement to take it at night, but the evening timing is a guideline-recommended practice.
My child has been acting differently since starting montelukast — is that normal?
Behavioral changes — including agitation, anxiety, sleep disturbances, aggression, and mood shifts — are known adverse effects of montelukast and have led to the FDA requiring a black box warning. Children may be particularly susceptible. If you notice any neuropsychiatric changes after starting montelukast, contact your prescriber promptly. These effects typically resolve after discontinuation. Do not stop the medication abruptly without medical guidance, but alert your doctor immediately.
Is montelukast as effective as inhaled corticosteroids for asthma?
No. Multiple clinical trials and meta-analyses demonstrate that low-dose inhaled corticosteroids (ICS) provide superior asthma control compared to montelukast monotherapy in most patients. Montelukast is considered an alternative for patients who refuse or cannot use ICS, or as an add-on therapy to ICS for better control. For allergic rhinitis, intranasal corticosteroids and antihistamines also generally outperform montelukast. The drug's strength lies in its ease of use (one oral tablet daily) and efficacy in specific subgroups such as exercise-induced bronchoconstriction and aspirin-exacerbated disease.
Can montelukast treat hives or eczema?
Montelukast has been studied off-label for chronic urticaria (hives) and atopic dermatitis, with some evidence of benefit — leukotrienes play a role in these conditions. However, it is not FDA-approved for these indications, and evidence for eczema is less robust. Antihistamines and, for eczema, topical corticosteroids and newer biologics (dupilumab) are the established treatments. Montelukast may be considered by clinicians as an adjunctive option in specific patients who don't respond to first-line therapy.
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