Medication Information Leaflet

What is this medicine used for?

Montelukast prevents swelling of the airways and is used to prevent and treat asthma and allergic rhinitis. It can also be used for other conditions as determined by your doctor.

How should I take/use this medication?

  • Take exactly as how your healthcare professional has told you.

  • Do not stop taking your medication without checking with your healthcare professional.

  • You may take this medication with or without food. 

  • If you are taking Montelukast granules, it can be mixed with a spoonful of cold or room temperature soft food, such as ice cream, rice or steamed carrots. The medication must be taken within 10 to 15 minutes after the medication packet is opened. You should not dissolve the granules in water, but you can drink water to help swallow down the granules.

  • If you are taking the Montelukast chewable tablets, chew well before swallowing.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if: 

  • You are allergic to this medication or any of the other ingredients of this medication.

  • You are pregnant, planning to become pregnant, or breastfeeding.

  • You are taking any other medications, including supplements, traditional medications and herbal remedies. 

What are some common side-effects of this medication?

The side effects for Montelukast are usually mild and generally well tolerated. They include the following: 

  • Sore throat

  • Infection of the airways

  • Stomach pain, diarrhoea, nausea

  • Headache

  • Feeling tired

  • Skin rashes

  • Numbness in hands and feet

These symptoms may happen but should get better over time. Check with your doctor if any of these symptoms are serious or do not go away.

What are some rare but serious side-effects that I need to seek medical advice immediately?

In some cases, this medication may be associated with the following changes to a person’s mental condition, especially in the first few weeks of treatment.

  • Mood or behaviour changes

  • Sleep disturbances

  • Worsening agitation, restlessness or, violent behaviour

  • New or worsening thoughts of harming yourself or ending your life

Please inform your doctor as soon as possible if you experience the above symptoms, or for your family or caregiver to inform your doctor if you are unable to seek treatment on your own.

Patients and parents/caregivers should stop Montelukast and discuss with their healthcare professional right away if you or your child experience behaviour or mood-related changes while taking the medication.

It is important to note that your doctor has prescribed this medication as he/she feels you will benefit more from taking this medication over the possible risks that it may cause. The risks of having these adverse effects are low. Most people take this medication without any of such problems.

The symptoms of a drug allergy include one or more of the following:

  • Swollen face/eyes/lips/tongue

  • Difficulty in breathing

  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How should I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Nov 2021

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