SummaryMontelukast 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 warningadditional 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 doHealth 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.BackgroundThe 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 usA 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 PIThe following boxed warning will be included in the Australian PIs for montelukast products.WARNING:Serious neuropsychiatric eventsNeuropsychiatric 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 eventsPrescribers 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 readingTGA Montelukast Safety Review, July 2018: Montelukast safety reviewACM April 2018 meeting: ACM meeting statement, Meeting 8, 5-6 April 2018ACM August 2024 meeting: ACM meeting statement, Meeting 46, 1 and 2 August 2024What 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 interactionssuspected 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 or contact our Pharmacovigilance Branch ADR.Reports@health.gov.au.DisclaimerMedicines 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.© Commonwealth of Australia 2025This work is copyright. You may reproduce the whole or part of this work in unaltered form for your own personal use or, if you are part of an organisation, for internal use within your organisation, but only if you or your organisation do not use the reproduction for any commercial purpose and retain this copyright notice and all disclaimer notices as part of that reproduction. Apart from rights to use as permitted by the Copyright Act 1968 or allowed by this copyright notice, all other rights are reserved, and you are not allowed to reproduce the whole or any part of this work in any way (electronic or otherwise) without first being given specific written permission from the Commonwealth to do so. Requests and inquiries concerning reproduction and rights are to be sent to the TGA Copyright Officer, Therapeutic Goods Administration, PO Box 100, Woden ACT 2606 or emailed to tga.copyright@tga.gov.au.For the latest safety information from us, subscribe to the TGA Safety Information email list via our website.For correspondence or further information about Medicines Safety Update, contact our Pharmacovigilance Branch at ADR.Reports@health.gov.au.Medicines Safety Update is written by staff from our Pharmacovigilance Branch.Editor: Dr Megan HickieDeputy Editor: Lucy Tumanow-WestContributors: My Di Luu and Emma Knott
Brief
On December 18, 2024, the Therapeutic Goods Administration (TGA) issued an update regarding montelukast. 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). The TGA added a new boxed warning and updated product information to highlight serious neuropsychiatric events, including behavioral changes, depression, and suicidal thoughts and behavior.
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Purpose
The purpose of this update is to inform health professionals, patients, and caregivers about the additional safety information being added to all montelukast products to strengthen and highlight existing warnings about serious neuropsychiatric events. These include behavioral changes, depression, and suicidal thoughts and behavior.
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). The update aims to bring the Australian Product Information (PI) and Consumer Medicine Information (CMI) in line with international regulatory advice.
The safety information includes a new boxed warning and additional guidance for prescribers and patients on the management of serious neuropsychiatric events. This follows a Therapeutic Goods Administration (TGA) safety investigation conducted in 2024 after international regulators strengthened warnings about neuropsychiatric events for montelukast products.
Effects on Industry
The update will have immediate effects on the pharmaceutical industry, particularly companies that manufacture and distribute montelukast products. They will be required to revise their product information and labeling to include the new boxed warning and additional guidance for prescribers and patients.
Pharmacies and healthcare providers may also need to review their procedures for managing patients taking montelukast, including monitoring for neuropsychiatric reactions and providing education on the risks associated with the medication.
Consumers will be affected by the update as they will receive revised product information and labeling that highlights the serious neuropsychiatric events associated with montelukast. This may lead to increased awareness and vigilance among patients and caregivers when taking or prescribing the medication.
Relevant Stakeholders
The following stakeholders are relevant to this update:
- Health professionals, including doctors, pharmacists, and nurses, who prescribe and dispense montelukast products.
- Patients and caregivers of patients taking montelukast, particularly those with a history of neuropsychiatric events or at high risk for these reactions.
- Pharmaceutical companies that manufacture and distribute montelukast products, including their marketing and sales teams.
- Healthcare providers, including hospitals, clinics, and pharmacies, which will need to update their procedures and policies for managing patients taking montelukast.
Next Steps
To comply with this update, pharmaceutical companies will be required to revise their product information and labeling to include the new boxed warning and additional guidance for prescribers and patients. Health professionals will need to review and update their procedures for managing patients taking montelukast, including monitoring for neuropsychiatric reactions and providing education on the risks associated with the medication.
Patients and caregivers should be advised to be alert for changes in behavior or for new neuropsychiatric symptoms when taking montelukast, and to discontinue the medication and contact a healthcare provider immediately if these events occur.
Any Other Relevant Information
The update is based on a TGA safety investigation conducted in 2024 after international regulators strengthened warnings about neuropsychiatric events for montelukast products. The investigation evaluated the medical literature and included consultation with international regulators and expert advice from the Advisory Committee on Medicines (ACM).
The ACM concluded that up-to-date information did not identify any new neuropsychiatric risks, but existing evidence for the association between montelukast and neuropsychiatric risks remained uncertain. As a result, the TGA recommended adding a boxed warning in the Australian PI to align with international regulators.
A search of the TGA’s 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, anxiety, suicidal ideation, depression, insomnia, and nightmares. There were 91 reports that mentioned suicidal behaviors, with 10 reports indicating a fatal outcome.
