Montelukast is used to treat and prevent asthma and allergic rhinitis. It may also be used for other conditions as determined by your doctor.
Asthma is a condition that affects the lung and makes it harder to breathe. It can cause wheezing, coughing, chest tightness and shortness of breath.
Allergic rhinitis is the inflammation of the nose. It can cause sneezing, itchy nose, blocked or runny nose symptoms.
Montelukast blocks certain substances in the body called leukotrienes that cause inflammation of the airways and nose in asthma, or allergic rhinitis.
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.
Inform your healthcare professional if:
Montelukast should not be used to treat sudden asthma attacks. You should have your rescue inhaler available for emergency use.
Do not suddenly stop taking your prescribed steroid inhaler for asthma control when starting this medication. Your doctor will help you reduce the steroid dose gradually if needed.
There are no specific food restrictions with this medication. However, if you are sensitive to aspirin or have aspirin-sensitive asthma, continue to avoid aspirin and other anti-inflammatory medications while taking montelukast.
Most people tolerate this medication well. Some possible side effects include:
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.
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.
You can also find out about drug allergies by watching these videos:
For videos in 中文, Melayu and தமிழ், click here
Rare but important neuropsychiatric side effects have been reported with Montelukast.
These include changes in mood, behaviour, or thinking. This may occur during treatment with Montelukast, or after stopping the medication, in patients with and without a history of mental health issues.
Your doctor will discuss the risk and benefits of using Montelukast with you.
Please inform your doctor as soon as possible, or for your family or caregiver to inform your doctor if you are unable to seek treatment on your own, should any of the following occur:
Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.
Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.
Disclaimers
Please take note that the above is not a complete list of all possible side-effects. If you have any concerns about your medication or if you have other side-effects that you think are caused by this medication, please consult your doctor or pharmacist. 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 (NHG Health, 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 June 2026
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