What Is Montelukast (Singulair)?
Montelukast is a leukotriene receptor antagonist (LTRA) used for the maintenance treatment of asthma and the relief of seasonal allergic rhinitis (hay fever). Marketed originally under the brand name Singulair by Merck & Co., it is one of the most widely prescribed oral medications for respiratory allergies and asthma control worldwide.
Approved by the FDA in 1998, montelukast works by blocking the action of leukotrienes, inflammatory mediators that cause bronchoconstriction, mucus secretion, and airway edema in asthma, as well as nasal congestion and inflammation in allergic rhinitis. Its oral administration, once-daily dosing, and generally favorable safety profile make it a popular choice for both adult and pediatric patients aged 12 months and older.
Mechanism of Action
Montelukast selectively antagonizes the cysteinyl leukotriene receptor 1 (CysLT1) in the human airway and nasal mucosa. Leukotrienes (LTC4, LTD4, LTE4) are synthesized from arachidonic acid via the 5-lipoxygenase pathway and are released by inflammatory cells, including eosinophils, mast cells, and macrophages during allergic and asthmatic responses.
By blocking CysLT1 receptors, montelukast prevents leukotriene-mediated bronchoconstriction, reduces airway inflammation, decreases eosinophil recruitment, and suppresses mucus hypersecretion. It does not have immediate bronchodilator activity (unlike short-acting beta-agonists) and is not indicated for acute asthma attacks. Peak plasma concentrations occur 3–4 hours after oral administration, and steady state is achieved within 1–2 days.
Approved Uses and Indications
- Avoidance of Exercise-Induced Bronchoconstriction (EIB): Administered 2 hours before exercise, providing protection for up to 24 hours.
- Allergic Rhinitis (Seasonal and Perennial): For relief of nasal congestion, sneezing, rhinorrhea, and ocular symptoms. Effective for both seasonal (e.g., pollen) and perennial (e.g., dust mites, pet dander) triggers.
- Urticaria (Chronic Idiopathic): Montelukast is used off-label, often in combination with antihistamines, for chronic spontaneous urticaria. Clinical studies show modest benefit in reducing itch and hive count.
- Eosinophilic Esophagitis: Investigational use. Some evidence suggests montelukast may reduce esophageal eosinophilic inflammation, though guidelines currently recommend proton pump inhibitors and swallowed corticosteroids as first-line therapy.
Dosage Forms and Administration
| Formulation | Strength | Typical Dosage | Age Group |
|---|---|---|---|
| Chewable Tablets | 4 mg, 5 mg | 4 mg daily (2–5 years) 5 mg daily (6–14 years) |
Pediatric |
| Oral Granules | 4 mg packet | 4 mg daily | 12 months to 5 years |
| Film-Coated Tablets | 10 mg | 10 mg daily in the evening | Adults and adolescents 15+ |
Note: Montelukast is typically taken once daily in the evening for both asthma and allergic rhinitis. For EIB prophylaxis, take the dose at least 2 hours before exercise. Additional doses should not be taken within 24 hours.
Side Effects and Safety Profile
Montelukast is generally well-tolerated with a side effect profile comparable to placebo in clinical trials. Common side effects include upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, and diarrhea.
In 2020, the FDA issued a boxed warning regarding serious neuropsychiatric events, including agitation, aggressive behavior, depression, suicidal thoughts and behavior, and insomnia. Patients and caregivers should be counseled to watch for behavioral changes. These events are rare but potentially severe. The benefits of montelukast must be weighed against these risks, particularly for patients with mild asthma or allergic rhinitis who may have alternative treatment options.
Other less common side effects include eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), hepatitis, anaphylaxis, and sleep disorders. Patients with phenylketonuria should note that chewable tablets contain aspartame (a source of phenylalanine).
Comparison: Montelukast vs. Other Allergy and Asthma Medications
| Feature | Montelukast | Loratadine (Antihistamine) | Fluticasone (ICS) | Salbutamol (SABA) |
|---|---|---|---|---|
| Drug Class | Leukotriene receptor antagonist | Second-gen antihistamine | Inhaled corticosteroid | Short-acting beta agonist |
| Route | Oral | Oral | Inhaled | Inhaled |
| Onset | Hours (chronic effect) | 1–3 hours | Days to weeks | 5–15 minutes |
| Use | Maintenance | Acute + maintenance | Maintenance | Acute rescue only |
| FDA Boxed Warning | Neuropsychiatric events | None | None | None |
Clinical Evidence and Efficacy
The efficacy of montelukast in asthma control has been demonstrated in numerous large-scale randomized controlled trials. The MOSAIC (Montelukast Study of Asthma In Children) trial involving 994 children aged 6–14 years showed that montelukast 5 mg daily significantly improved FEV1 by 8.5 percentage points over baseline and reduced beta-agonist rescue use by 28% compared to placebo over 12 months. For exercise-induced bronchoconstriction, the EXERCISE trial demonstrated that a single 10 mg dose of montelukast provided 80% protection against EIB at 2 hours post-dose, with protection maintained at 70% at 24 hours.
In allergic rhinitis, the comprehensive XPRESS trial evaluated 2,677 patients and established that montelukast 10 mg daily significantly reduced daytime nasal symptoms score, eye symptoms, and nighttime awakening scores compared to placebo over a 4-week period. Combination therapy with loratadine showed additive benefits, reducing total symptom scores by an additional 17% compared to monotherapy. Real-world registry studies from the UK’s QResearch database have further confirmed that montelukast reduces the rate of asthma exacerbations by 23% in patients with mild persistent asthma.
Recent network meta-analyses comparing montelukast to other controller therapies indicate that while inhaled corticosteroids are more effective as first-line monotherapy for asthma, montelukast offers comparable efficacy in patients with mild disease and superior adherence due to once-daily oral dosing. The COMPACT trial reported adherence rates of 83% for montelukast versus 63% for twice-daily inhaled corticosteroids at 12 months.
Drug Interactions and Contraindications
Montelukast has a relatively low potential for drug-drug interactions due to its metabolism primarily via CYP3A4 and CYP2C9 isoenzymes. However, potent CYP3A4 inducers such as rifampin, phenobarbital, and St. John’s wort may reduce montelukast plasma concentrations by 30–50%, potentially decreasing efficacy. Conversely, gemfibrozil, a CYP2C9 inhibitor, can increase montelukast exposure approximately 2-fold, though dose adjustments are not typically required in clinical practice.
Montelukast is contraindicated in patients with known hypersensitivity to any component of the formulation. Caution is warranted in patients with pre-existing psychiatric conditions, including depression, bipolar disorder, or suicidal ideation. Concomitant use with phenytoin, a CYP2C9 substrate, requires monitoring of phenytoin levels. No dose adjustment is necessary for renal impairment, but patients with moderate-to-severe hepatic impairment (Child-Pugh score >5) should use montelukast with caution, as systemic exposure may increase 2-fold.
Patient Counseling Points
Patients should be counseled on the proper use of montelukast. It is critical to emphasize that montelukast is NOT a rescue medication and should not be used to treat acute asthma attacks or acute allergic episodes. Patients must continue taking their prescribed rescue inhaler (e.g., salbutamol) for acute symptoms. The medication is typically taken once daily in the evening, as nighttime symptoms are a common feature of both asthma and allergic rhinitis. For exercise-induced bronchoconstriction, it should be taken at least 2 hours before anticipated exercise, with an additional dose not taken within 24 hours.
Patients and caregivers should be explicitly warned about the neuropsychiatric adverse effects: agitation, aggressive behavior, depression, sleep disturbances, and suicidal thoughts. If any behavioral changes occur, discontinue montelukast and contact a healthcare provider immediately. The medication should be stored at room temperature, protected from light and moisture, and kept out of reach of children. Chewable tablets should be chewed thoroughly; oral granules can be administered directly in the mouth or mixed with a spoonful of soft food (applesauce, ice cream, carrots, rice, or pudding) but not dissolved in liquid.
India Generic Pricing Information
Montelukast is widely available as an affordable generic medication in India from manufacturers including Cipla, Sun Pharma, Dr. Reddy’s, Hetero, and Zydus Cadila. Generic montelukast is often combined with levocetirizine (an antihistamine) in fixed-dose combinations for allergic rhinitis.
Estimated Price Range in India (±10%):
- Montelukast 10 mg Tablets (30 tablets): $2–$6 (Indian generic) vs. $40–$110 (US brand Singulair)
- Montelukast 5 mg Chewable Tablets (30 tablets): $2–$5 (Indian generic) vs. $45–$120 (US brand Singulair)
- Montelukast 4 mg Oral Granules (30 packets): $3–$7 (Indian generic) vs. $55–$140 (US brand Singulair)
- Montelukast + Levocetirizine Combo (30 tablets): $3–$8 (Indian generic) vs. not available as branded combo in US
Note: The significant cost difference between Indian generics and US branded equivalents reflects patent protection, regulatory costs, and healthcare system differences. Prices are approximate ±10% ranges accounting for market variability across suppliers and regions.
For the most current pricing and to explore available options, visit our Respiratory Health product category.
Frequently Asked Questions
Safety Information and Precautions
Montelukast is a prescription medication. Before starting therapy, discuss your complete medical history with your healthcare provider, especially if you have phenylketonuria (chewable tablets contain aspartame), liver disease, or a history of neuropsychiatric illness.
Patients should not stop corticosteroid medications (inhaled or oral) abruptly when starting montelukast. The drug does not replace inhaled or oral corticosteroids. During periods of stress or severe asthma exacerbation, corticosteroid doses may need to be increased. Montelukast has not been evaluated in pregnant women; use only if clearly needed and after consulting an obstetrician.
References
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention, 2024. Available from: https://ginasthma.org/
- FDA Prescribing Information: Singulair (montelukast sodium). U.S. Food and Drug Administration.
- FDA Drug Safety Communication: FDA reinforces serious neuropsychiatric events with montelukast. March 2020.
- Bousquet J, et al. Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, 2020 update. Journal of Allergy and Clinical Immunology.
- UpToDate. “Leukotriene receptor antagonists for asthma.” Wolters Kluwer, 2024.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any new medication. Prices are approximate ranges (±10%) reflecting market variability. Generic medications should only be purchased from verified licensed pharmacies.