More prominent safety warnings about the neuropsychiatric effects of montelukast

Summary

Montelukast is a prescription medicine used to prevent and treat chronic asthma in adults and children aged 2 years and older, and for symptomatic seasonal allergic rhinitis (hay fever). 

Additional safety information is being added to all montelukast products to strengthen and highlight existing warnings about serious neuropsychiatric events. These include behavioural changes, depression and suicidal thoughts and behaviour. The safety information includes:

• a new boxed warning
• additional guidance for prescribers and patients on the management of serious neuropsychiatric events. 

This safety update follows a TGA safety investigation conducted in 2024 after international regulators strengthened warnings about neuropsychiatric events for montelukast products. 

The update brings the Australian Product Information (PI) and Consumer Medicine Information (CMI) in line with international regulatory advice. 

What health professionals should do

Health professionals are reminded about the potential neuropsychiatric effects associated with montelukast. These effects have been reported in all age groups taking montelukast, are generally mild and may occur by chance. However, symptoms can be serious and continue if treatment is not stopped. In rare cases, patients taking montelukast have died after experiencing suicidal behaviour. 

Health professionals should be vigilant for neuropsychiatric reactions in patients taking montelukast and discontinue treatment if new or worsening symptoms occur.

Advise patients and their carers to be alert for changes in behaviour or for new neuropsychiatric symptoms and to seek medical advice immediately should they occur. Consider providing the CMI to remind patients of these effects.

Background

The risks of neuropsychiatric events with montelukast are already well documented in both the PI and CMI. 

In July 2018, the TGA published a review of montelukast and neuropsychiatric adverse events. This evaluated the medical literature and included consultation with international regulators and expert advice from the Advisory Committee on Medicines (ACM).

In 2024, an updated TGA safety investigation was conducted after international regulators strengthened their warnings about neuropsychiatric events. Expert advice from the ACM concluded that up-to-date information did not identify any new neuropsychiatric risks and existing evidence for the association between montelukast and neuropsychiatric risks remained uncertain. 

The expert group recommended adding a boxed warning in the Australian PI to align with international regulators. 

Adverse events reported to us

A search of our publicly available Database of Adverse Event Notifications (DAEN) on 18 December 2024 identified 356 cases for montelukast and psychiatric disorders. 

The most commonly reported symptoms were aggression (100 cases), anxiety (87 cases), suicidal ideation (72 cases), depression (71 cases), insomnia (52 cases) and nightmare (50 cases). 

There were 91 reports that mentioned suicidal behaviours. Of these, 10 reported a fatal outcome.

‌It is important to note that inclusion in the DAEN does not mean that the details of the reported event have been confirmed, or that the event has been determined to be related to a medicine.‌

Updates to the PI

The following boxed warning will be included in the Australian PIs for montelukast products.

WARNING:

Serious neuropsychiatric events

Neuropsychiatric events such as behavioural changes, depression and suicidality have been reported in all age groups taking montelukast (see sections 4.4 and 4.8). Events are generally mild and may be coincidental. However, the symptoms may be serious and continue if the treatment is not withdrawn. Therefore, the treatment with montelukast should be discontinued if neuropsychiatric symptoms occur during treatment. Advise patients and/or caregivers to be alert for neuropsychiatric events and instruct them to notify their physician if these changes in behaviour occur.

Additional advice to prescribers will also be included in the existing information on neuropsychiatric events in Section 4.4 Special warnings and precautions of the PI, as follows:

Neuropsychiatric events

Prescribers should discuss the benefits and risks of montelukast use with patients and caregivers when prescribing montelukast. Patients and/or caregivers should be advised to be alert for changes in behaviour or for new neuropsychiatric symptoms when taking montelukast. If changes in behaviour are observed, or if new neuropsychiatric symptoms or suicidal thoughts and/or behaviour occur, patients should be advised to discontinue montelukast and contact a healthcare provider immediately. In many cases, symptoms resolved after stopping montelukast therapy; however, in some cases symptoms persisted after discontinuation of montelukast. Therefore, patients should be monitored and provided supportive care until symptoms resolve. Prescribers should carefully evaluate the risks and benefits of continuing treatment with montelukast if such events occur.

Further reading

TGA Montelukast Safety Review, July 2018: Montelukast safety review

ACM April 2018 meeting: ACM meeting statement, Meeting 8, 5-6 April 2018

ACM August 2024 meeting: ACM meeting statement, Meeting 46, 1 and 2 August 2024

What to report? You don't need to be certain, just suspicious!

We encourage the reporting of all suspected adverse reactions to medicines, including vaccines, over-the-counter medicines, and herbal, traditional or alternative remedies.

We particularly request reports of:

• all suspected reactions to new medicines (look for the Black Triangle ▼ in PI and CMI documents – this symbol identifies medicines that are new or being used differently)
• all suspected medicines interactions
• suspected reactions causing death, admission to hospital or prolongation of hospitalisation, increased investigations or treatment, or birth defects.

To report a suspected side effect or for more information about reporting, go to our ‘Report problem or side effect’ webpage.

Disclaimer

Medicines Safety Update is aimed at health professionals. It is intended to provide practical information to health professionals on medicine safety, including emerging safety issues. The information in Medicines Safety Update is necessarily general and is not intended to be a substitute for a health professional's judgment in each case, taking into account the individual circumstances of their patients. Reasonable care has been taken to ensure that the information is accurate and complete at the time of publication. The Australian Government gives no warranty that the information in this document is accurate or complete, and shall not be liable for any loss whatsoever due to negligence or otherwise arising from the use of or reliance on this document.

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Medicines Safety Update is written by staff from our Pharmacovigilance Branch.

Editor: Dr Megan Hickie

Deputy Editor: Lucy Tumanow-West

Contributors: My Di Luu and Emma Knott