Leukotriene Receptor Antagonist — Asthma Prophylaxis / Allergic Rhinitis Pregnancy: Use with caution — limited human data; continue if controlling asthma effectively in pregnancy (uncontrolled asthma more dangerous than drug)

Montelukast (Paediatric)

Brand names: Singulair

Adult dose

Dose: 10 mg once daily in the evening

Route: Oral

Frequency: Once daily (evening)

Max: 10 mg/day

Adult reference — see paediatric dose section

Paediatric dose

Route: Oral (granules, chewable tablet, or standard tablet)

Frequency: Once daily in the evening

Max: Age-banded fixed doses

BNFc: 6 months–5 years: 4 mg granules once daily; 6–14 years: 5 mg chewable tablet once daily; ≥15 years: 10 mg tablet once daily. Granules (4 mg) can be mixed with one teaspoon of cold soft food (not liquids unless administered immediately). Added as step-up to ICS if not controlled, or alternative to ICS in mild persistent asthma. Also licensed for allergic rhinitis and exercise-induced bronchoconstriction.

Dose adjustments

Renal

No dose adjustment required

Hepatic

Use with caution in severe hepatic impairment

Clinical pearls

FDA/MHRA black box warning (2020): neuropsychiatric events including suicidal ideation and behaviour — counsel patients and carers at initiation; reassess benefit-risk periodically; discontinue if neuropsychiatric symptoms develop
Particularly effective in allergic (atopic) asthma with concomitant allergic rhinitis — leukotriene pathway is central to both conditions; Churg-Strauss vasculitis association if oral corticosteroids withdrawn revealing eosinophilic disease
Not a bronchodilator — does not treat acute asthma attacks; used for prophylaxis only; continue reliever SABA
Exercise-induced asthma: montelukast taken 2 hours before exercise prevents EIA — useful in children in whom beta-blockers are contraindicated

Contraindications

Hypersensitivity to montelukast

Side effects

Neuropsychiatric effects (nightmares, sleep disturbance, agitation, aggression, depression, suicidal ideation — MHRA/FDA black box warning)
Headache
GI disturbance
Rash
Elevated LFTs (rare)
Eosinophilia (Churg-Strauss if steroids reduced)

Interactions

Rifampicin — reduces montelukast levels (CYP3A4 induction)
Phenobarbital — reduces montelukast levels
Gemfibrozil — increases montelukast levels

Monitoring

Neuropsychiatric symptoms (at each review — specifically ask about sleep, mood, behaviour)
Asthma control and symptom diary
Lung function tests (spirometry when age-appropriate)
Eosinophil count (if Churg-Strauss concern)

Reference: BNF for Children; MHRA Drug Safety Update 2020 (Montelukast Neuropsychiatric); NICE NG80 (Asthma); BTS/SIGN Asthma Guideline 2023. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways