Outcome of MHRA review of neuropsychiatric reactions with montelukast

More prominent warnings are to be added to the leaflet that is provided with every pack of montelukast (Singulair) in the UK, reminding patients and healthcare professionals that they should be alert to serious behaviour and mood-related changes (neuropsychiatric reactions) associated with the treatment.

Healthcare professionals must make patients and their caregivers aware of this information. Patients should immediately speak to their prescriber or seek urgent medical attention if neuropsychiatric reactions occur. The Medicines and Healthcare products Regulatory Agency (MHRA) issued this guidance today through its Drug Safety Update (DSU).

A range of neuropsychiatric reactions have been reported in people taking montelukast, an oral add-on therapy for the treatment of asthma in patients aged 6 months and older. The most frequently reported neuropsychiatric reactions among all age groups are sleep disorders, hallucinations, anxiety and depression, and changes in behaviour and mood.

While the benefits of montelukast continue to outweigh the risks for most patients for the management of asthma, the MHRA has continued to receive Yellow Card reports from patients and caregivers since our last Drug Safety Update article in 2019, including some raising concerns about a potential lack of awareness of the risk of neuropsychiatric reactions.

The MHRA has conducted a thorough review of the evidence which confirmed that while the risk of neuropsychiatric reactions with montelukast remains unchanged, Yellow Card reports have indicated this risk is potentially not well known by healthcare professionals, patients and their caregivers.

In response, new boxed warnings are being added to the patient information leaflets (PIL) which are supplied with every montelukast product in the UK to make these risks more prominent to the reader. These reactions are typically uncommon, and more serious reactions such as hallucinations, disorientation and suicidal thoughts and actions are very rare.

Dr Alison Cave, MHRA Chief Safety Officer, said:

Patient safety is our top priority. Throughout our review, we have listened to patient representatives and taken independent clinical advice from paediatricians, specialists in mental and respiratory health and experts from the Commission on Human Medicine’s Expert Advisory Groups.

We have now taken regulatory action to update the leaflet included in all montelukast medicine packs in the UK with prominent warnings and advice about the risk of serious behaviour and mood-related changes. Healthcare professionals should inform patients of these potential side effects. Patients and carers should immediately speak to their prescriber or seek urgent medical attention if the patient experiences any neuropsychiatric symptoms while using montelukast.

We keep all medicines under continuous review to ensure that the benefits outweigh the risks for most patients. We encourage patients, healthcare professionals and carers to report any suspected side effects with montelukast to the Yellow Card scheme.

The risk of neuropsychiatric side effects has been included in the product information for montelukast since 2008, and following a European review in 2019, additional warnings about these risks were included in the EU and UK product information. A Drug Safety Update article was also published in the UK by the MHRA to remind prescribers of the risk.

Notes to Editors

  • Further information is available in the Drug Safety Update.
  • For further help and information on mental health issues, please go to the NHS website (Self-harm and Suicidal thoughts.
  • A Summary of Product Characteristics (SmPC) is a description of a medicinal product’s properties and the conditions attached to its use. It explains how to use and prescribe a medicine. It is used by healthcare professionals, such as doctors, nurses and pharmacists. Since first authorised in the UK in 1998, approximately 44 million prescriptions of montelukast have been issued. During this time, the MHRA has received 1,223 reports of suspected neuropsychiatric adverse reactions. These include:
    • sleep disturbances, depression and agitation including aggressive behaviour (may affect up to 1 in 100 people taking montelukast)
    • disturbances of attention or memory (up to 1 in 1,000 people)
    • very rarely, hallucinations and suicidal thinking and behaviour (up to 1 in 10,000 people)
  • Boxed warnings are warnings in an outlined black box on the Patient Information Leaflets and Summary of Product Characteristics.
  • The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe.  All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks. 
  • The MHRA is an executive agency of the Department of Health and Social Care. 
  • For media enquiries, please contact 020 3080 7651 or [email protected].


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