Pharmacology · Leukotriene modifiers
Montelukast !
An oral leukotriene receptor blocker used as an add-on asthma controller and to prevent exercise-induced bronchoconstriction. Watch mood and sleep.
Updated 2026-11-01
No structure of montelukast on CysLT1 exists. The figure shows zafirlukast, another antagonist of the same receptor and site, bound to human CysLT1.
Mechanism of action
Montelukast binds the CysLT1 receptor with high affinity and selectivity and blocks leukotriene D4 there, without any agonist effect. Cysteinyl leukotrienes released by mast cells and eosinophils would otherwise contract airway smooth muscle, increase mucus and oedema and attract eosinophils. Blocking them reduces bronchoconstriction and airway inflammation in asthma and nasal symptoms in allergic rhinitis.
- Mast cells and eosinophils release cysteinyl leukotrienes
- Montelukast blocks LTD4 at the CysLT1 receptor
- Airway muscle contraction, mucus and oedema decrease
- Asthma symptoms and exercise bronchoconstriction fall
Pharmacokinetics
- Absorption
- Well absorbed by mouth; food does not change it much
- Metabolism
- Extensively metabolised in the liver, mainly by CYP2C8 (also 3A4 and 2C9)
- Elimination
- Almost entirely in bile
- Half-life
- About 3 to 6 hours in healthy adults
Indications
- Prophylaxis and chronic treatment of asthma, as add-on controller Asthma →
- Prevention of exercise-induced bronchoconstriction
- Allergic rhinitis when other treatments fail or are not tolerated Allergic rhinitis →
Adverse effects
Common
- Headache
- Upper respiratory infection, pharyngitis and cough
- Abdominal pain and diarrhoea
- Fever and ear infection in children
Contraindications
- Hypersensitivity to any component
- Not for treating an acute asthma attack
- Patients with aspirin-sensitive asthma keep avoiding aspirin and NSAIDs
- Chewable tablets contain phenylalanine (phenylketonuria)
Key interactions
- Phenobarbital and other strong enzyme inducers (rifampicin)
- Lower montelukast levels; clinical response is watched
- Gemfibrozil
- Raises montelukast exposure several-fold
What is monitored
- Mood, behaviour and sleep, in children and adults
- Asthma control
- Rash, numbness or worsening breathing when oral steroids are reduced
Administration and safety
- Given by mouth as tablets, chewable tablets or granules
- It is not a reliever and does not replace inhaled or oral steroids abruptly
Nursing care
- Before starting, ask about previous mental health problems
- Teach the patient and family to report mood changes, nightmares, aggression or suicidal thoughts at once
- Make sure a short-acting reliever is available for attacks
- In phenylketonuria, check the formulation (chewable tablets contain phenylalanine)
Pregnancy and breastfeeding
Cohort studies over decades have not shown a higher risk of major birth defects with montelukast.
Test yourself
Think of the answer, then tap the question to see it.
What is the mechanism of montelukast?
Selective antagonism of the CysLT1 receptor, blocking leukotriene D4 and its bronchoconstriction, mucus and eosinophil recruitment.
What boxed warning does montelukast carry?
Serious neuropsychiatric events, including agitation, sleep disturbance, depression and suicidal thoughts or behaviour.
Which vasculitis may appear when oral steroids are tapered in a patient on montelukast?
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), with systemic eosinophilia.
Is montelukast used to treat an acute asthma attack?
No. It is an oral add-on controller; acute attacks are treated with a short-acting beta-2 agonist.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - MONTELUKAST SODIUM tablet, chewable MONTELUKAST SODIUM tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Montelukast: a medicine to prevent asthma symptoms - NHS (NHS, 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.