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About montelukast - Brand name: Singulair

Montelukast is used to prevent the symptoms of asthma. It's usually prescribed when asthma is mild and can stop it from getting worse.

It can also help people with asthma who have breathing difficulties when they exercise (exercise-induced asthma) and seasonal allergies, such as sneezing, itchiness and a blocked or runny nose (allergic rhinitis).

Montelukast is sometimes given to people without asthma to treat hives (urticaria) that last for more than 6 weeks.

It's only available on prescription. It comes as tablets or granules.


Do not use montelukast to treat an asthma attack. Always use your reliever inhaler.

Key facts

  • Montelukast helps stop your airways from narrowing (caused by inflammation). This makes breathing easier and prevents asthma attacks.
  • Most people take montelukast once a day in the evening.
  • If you take it for asthma, it's important to take it even when you have no symptoms.
  • You'll use montelukast alongside your inhalers or other asthma medicine.
  • Some common side effects include headaches and feeling or being sick.
  • Less common side effects include mood changes such as depression and anxiety, sleep problems such as nightmares, and changes in your behaviour such as aggression. Speak to your doctor as soon as possible if you notice any of these side effects.

Page last reviewed: 14 March 2023
Next review due: 14 March 2026