Montelukast is used to treat and prevent asthma symptoms. Find out how to take it safely and possible side effects.

Type of medicine Also called
  • Medicine for asthma
  • Montelukast Mylan
  • Apo-Montelukast

What is montelukast?

Montelukast is used to treat and prevent asthma symptoms. It is a type of anti-inflammatory medicine that comes in tablet form. Montelukast is generally less effective than steroid inhalers for most people with asthma. Montelukast is NOT used to treat an acute attack of asthma. Read more about asthma and medicines for asthma.  

Montelukast is also used to treat seasonal allergies such as hay fever.  

In New Zealand montelukast is available as tablets (10 mg) and chewable tablets (4 mg and 5mg).


  • Adults and children 15 years and older: 10 mg once a day.
  • Children 6–14 years old: 5 mg once a day.
  • Children 2–5 years old: 4 mg once a day.
  • Always take your montelukast exactly as your doctor has told you.
  • The pharmacy label on your medicine will tell you how much montelukast to take, how often to take it and any special instructions.

How to take montelukast

  • Timing: It is best to take montelukast in the evening. Take your tablet at the same time each day to help you remember. 
    • Tablets 10 mg: Swallow your tablet with a drink of water. You can take it before or after food.  
    • Chewable tablets (4 mg and 5 mg): Chew the tablet before swallowing. It is best to take the chewable tablet on an empty stomach, eg, 1 hour before food or 2 hours after food. Food can interfere with the absorption of this medicine.  
  • Missed dose: If you forget to take your dose, take it as soon as you remember that day. But if it is nearly time for your next dose, take the next dose at the right time. Do not take double the dose.

Precautions before taking montelukast

  • Are you pregnant or breastfeeding?

If so, it’s important that you tell your doctor or pharmacist before you start montelukast. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

What are the side effects of montelukast?

Like all medicines, montelukast can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Changes in behaviour or mood

Montelukast can cause changes in behaviour or mood including sleep problems, strange dreams, hallucinations, feeling anxious or agitated, irritability, restlessness, tremor, low mood, depression and suicidal thoughts.

Tell your doctor immediately or phone Healthline on 0800 611 116 if you or your child gets these side effects. 

Side effects What should I do?
  • Tummy pain
  • Nausea (feeling sick)
  • Diarrhoea (runny poo)
  • These are quite common when you start taking montelukast.   
  • These effects usually go away with time. 
  • Tell your doctor if troublesome.
  • Headache 
  • Muscle pain
  • Tell your doctor if troublesome.
  • Sleep problems
  • Strange dreams
  • Changes in behaviour or mood
  • Hallucinations ( (seeing, hearing, smelling, sensing things that others can’t)
  • Feeling anxious or agitated
  • Confusion
  • Suicidal thoughts
  • Tell your doctor immediately or phone Healthline on 0800 611 116.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

The following links have more information on montelukast:

Montelukast Mylan Medsafe Consumer Information Sheet, NZ
Apo-Montelukast Medsafe Consumer Information Sheet, NZ


  1. Montelukast NZ Formulary 
  2. The pharmacological management of asthma in adolescents and adults has changed BPAC, NZ, 2020
  3. Montelukast — Reminder about neuropsychiatric reactions Medsafe, NZ, 2017
Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 04 Oct 2021