Montelukast

Montelukast is a leukotriene receptor antagonist (LTRA) used in the management of asthma and allergic rhinitis.

It is taken as a once-daily tablet and works by blocking the CysLT1 receptor, preventing the action of leukotrienes — inflammatory mediators that contribute to bronchoconstriction, mucus production, and airway oedema.

Leukotrienes are released by mast cells, eosinophils, and other inflammatory cells in the airways. They are a key driver of the late-phase allergic response and exercise-induced bronchoconstriction.

By blocking their receptor, montelukast provides anti-inflammatory and bronchodilatory effects that complement inhaled corticosteroids.

Role in Asthma Management

Montelukast is used as add-on therapy to inhaled corticosteroids in patients whose asthma is not adequately controlled, or as an alternative to low-dose ICS in patients who cannot or will not use inhalers.

It is also licensed for the prevention of exercise-induced bronchoconstriction.

Allergic Rhinitis

Montelukast is effective for both seasonal and perennial allergic rhinitis and can be particularly useful in patients who have both asthma and nasal allergy, as a single tablet addresses both conditions.

How to Take Montelukast

Take one tablet in the evening, with or without food. The evening timing is based on the original clinical trial design and leukotriene release patterns. Swallow the adult tablet whole.

Chewable tablets for children should be chewed before swallowing.

Regularity

Take montelukast every day, even when symptom-free. It is a preventer, not a reliever. Continue your reliever inhaler for acute symptoms.

Asthma Action Plan

Do not stop montelukast during an asthma exacerbation. It should be continued alongside other treatments. Do not use it to replace an inhaled corticosteroid without medical advice.

Adults and Adolescents (15 years and over)

• 10 mg film-coated tablet once daily in the evening

Children 6-14 Years

• 5 mg chewable tablet once daily in the evening

Children 2-5 Years

• 4 mg chewable tablet or granules once daily in the evening

Children 6 Months to 2 Years

• 4 mg granules once daily in the evening

Renal and Hepatic Impairment

• No dose adjustment for mild to moderate hepatic impairment
• No dose adjustment for renal impairment
• Limited data in severe hepatic impairment

Common (up to 1 in 10 patients)

• Headache
• Abdominal pain
• Upper respiratory tract infection (in paediatric trials)

Uncommon (up to 1 in 100 patients)

• Diarrhoea, nausea, vomiting
• Rash, eczema
• Dizziness
• Fatigue

Rare (up to 1 in 1,000 patients)

• Sleep disturbance (insomnia, abnormal dreams, sleepwalking)
• Agitation, irritability, or restlessness
• Depression, anxiety
• Elevated liver transaminases
• Bruising, bleeding tendency

Very Rare (fewer than 1 in 10,000 patients)

• Suicidal thoughts and behaviour (see warnings)
• Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
• Hepatitis, including cholestatic and hepatocellular injury
• Erythema nodosum

Neuropsychiatric effects require particular vigilance. Report mood or behavioural changes promptly.

Neuropsychiatric Effects

Post-marketing reports include agitation, aggression, depression, suicidal thoughts, hallucinations, and sleep disturbance. These are uncommon but clinically important.

Patients and carers — especially parents of children taking montelukast — should be alert to mood or behavioural changes and report them immediately.

Not a Rescue Medication

Montelukast does not relieve acute bronchospasm. Always carry a short-acting bronchodilator.

Churg-Strauss Syndrome

Rarely, eosinophilic granulomatosis with polyangiitis has been reported in patients on montelukast, often during corticosteroid tapering.

It is unclear whether montelukast is a cause or whether the reduction in steroids unmasks a pre-existing condition.

Phenylketonuria

Chewable tablets contain aspartame, a source of phenylalanine. Patients with phenylketonuria should be informed.

Do not take montelukast if you have a known hypersensitivity to montelukast sodium or any excipient in the formulation.

Chewable tablets contain aspartame and should be used with caution in patients with phenylketonuria.

There are no other absolute contraindications, but the neuropsychiatric risk profile should be considered when initiating therapy, particularly in patients with a history of mental health disorders.