What it is used for
- Asthma (regular prevention, often alongside an inhaler)
- Preventing exercise-induced asthma symptoms
- Hay fever and allergic rhinitis (sometimes, especially with asthma)
- Reducing the frequency of asthma attacks
How it works
Montelukast blocks leukotrienes, chemicals the body releases that cause airway swelling, tightening, and mucus. By blocking them, it helps keep the airways open and reduces asthma and allergy symptoms.
How it is taken
Comes as tablets, chewable tablets, and granules (for young children). It is taken by mouth, often in the evening. It is a preventer taken regularly, not for sudden relief. Take it exactly as your doctor or pharmacist directs and as the label says.
No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.
Common side effects
- Headache
- Stomach pain or upset
- Cold-like symptoms or sore throat
- Diarrhoea
- Feeling thirsty
Serious effects — get help
- Mental health or mood changes — including agitation, anxiety, depression, sleep problems, unusual dreams, or thoughts of self-harm (seek urgent advice)
- Signs of a severe allergic reaction
- Numbness, tingling, or flu-like symptoms with rash (rare)
- Worsening breathing or wheeze
If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.
Interactions to watch
- Certain medicines for epilepsy (e.g. phenobarbital) and some others that affect liver enzymes
- Tell your clinician about all your medicines, including other asthma treatments
Who should take care
- Be aware of the risk of mood and behaviour changes — report any new mental health symptoms to a clinician promptly
- Tell your clinician if you are pregnant, planning pregnancy, or breastfeeding
- It does not relieve a sudden asthma attack — always keep a reliever inhaler
- Tell your clinician about a history of mental health conditions before starting