I refer the hon. member to the answer provided by the Department of Health and Social Care (DHSC) in January this year. https://questions-statements.parliament.uk/written-questions/detail/2026-01-12/104605

The Ministry of Defence (MOD) and DHSC recognise that mefloquine is associated with neurological and psychiatric adverse effects. Defence Medical Command (DMedC) support an approach to healthcare in which treatment is directed towards the patient’s clinical diagnosis and presenting symptoms and managed in accordance with current evidence-based clinical practice and relevant national guidance. DMedC is not aware of evidence or national guidance that recommends withholding otherwise appropriate treatments where clinically indicated, solely on the basis of previous mefloquine exposure.

The MOD will continue to review emerging evidence, including systematic reviews, regulatory advice from the Medicines and Healthcare products Regulatory Agency (MRHA) and recommendations from expert bodies concerned with malaria prevention.

As outlined in the response by the former Minister for Health Innovation and Safety, NHS England is considering adding screening for prior mefloquine use and any associated adverse events to initial Op COURAGE and Op RESTORE assessments.

The Defence Committee Report (HC567) made a series of recommendations on the Ministry of Defence (MOD) use of mefloquine (trade name Lariam), individual risk assessments, research undertaken research on mefloquine, and comparisons with the use of mefloquine by allies.

In response to the report, MOD introduced a new policy on prescribing antimalarial drugs on 12 September 2016. Anti-malaria drugs, including mefloquine, are only prescribed after a face-to-face individual risk assessment. The recommended anti-malaria drug is determined by the sensitivity of malaria parasites to those drugs in different parts of the world based on UKHSA guidance. Mefloquine is only prescribed by a doctor and after all other alternatives have been identified as unsuitable.

In all cases, the authority and supply details for anti-malarial drugs are recorded on the individual’s medical note. Personnel supplied with anti-malarial drugs are issued copies of all manufacturer-provided patient documentation relevant to that drug and are informed of all special warnings or precautions relevant to anti-malarial drugs.

The Department continues to monitor and publish bi-annual statistics on the number of mefloquine prescriptions given to UK Armed Forces personnel at MOD medical facilities.

The latest release of information can be found at the following link:

https://www.gov.uk/government/collections/mefloquine-lariam-prescribing-in-the-uk-armed-forces-statistics-index

The next release is due to be published on 28 May 2026 and will include data from 12 September 2016 to 31 March 2026.

The MOD continues to monitor the use of mefloquine and other anti-malarial drugs by allies. This includes the extent to and circumstances in which mefloquine is prescribed.

The Department previously outlined its intention to conduct a research proposal into the impact of adverse effects of anti-malaria drugs focusing on the performance of military personnel exercising in Kenya. The study, ‘Impact of anti-malarial chemoprophylaxis on functional effectiveness of military personnel’ (713/MODREC/15) was initiated and data on the impact of anti-malarial chemoprophylaxis on the functional effectiveness of military personnel collected from two British Army Training Unit Kenya (BATUK) battlegroups between 2017-18. Following a delay in the analysis of the data, the department intend to undertake further work to be able publish the findings in a peer reviewed journal in 2027.

Mefloquine, trade name Lariam, is recommended as an effective anti-malarial by international health agencies, including the World Health Organisation. Ministry of Defence (MOD) and the National Health Service both follow National Institute for Care and Excellence guidelines on the prescription and management of side effects associated with mefloquine.

MOD is engaged with NHS England (NHSE) through the NHSE Armed Forces Clinical Reference Group. This group has reviewed the clinical management of the side effects associated with mefloquine. As symptoms can resemble acute psychiatric conditions, clinicians are advised to assess patients individually and are expected to take a full drug and alcohol history, including any previous mefloquine use.

The side effects that may be experienced whilst taking, or with a history of having taken mefloquine, will be treated according to the diagnosis; for example, if the patient is experiencing depressive symptoms, the treatment for depression will be instigated.

Since 2016, MOD has admitted mefloquine can cause minor psychiatric injury in certain individuals for a limited period of time. Causation of long-term psychiatric injury is denied.

I would encourage any Veteran who is struggling with their mental health to self-refer or seek the support of their GP to access Op COURAGE, the Veterans' Mental Health and Wellbeing Service.

The Medicines and Healthcare products Regulatory Agency (MHRA) has updated its safety advice on mefloquine to reflect the risk of neuropsychiatric side effects, advising that it should not be used for chemoprophylaxis in individuals with a history of psychiatric disturbance.

National Institute for Health and Care Excellence guidance states that mefloquine should not be prescribed to people with current or past psychiatric disorders, suicidal ideation or behaviour, or with epilepsy or any form of convulsion.

The clinical management of suspected mefloquine intoxication has recently been reviewed with the NHS England Armed Forces Clinical Reference Group. This review advised that clinicians should assess patients individually and are expected to take a full drug and alcohol history, including any previous mefloquine use.

NHS England is considering adding screening for prior mefloquine use and any associated adverse events to initial Op COURAGE and Op RESTORE assessments. Additional clinical guidance on mefloquine and its potential adverse effects is being developed and through the Five Eyes partnership discussions are being arranged with the United States to support continuous learning and best practice in the management of suspected mefloquine intoxication.

Mefloquine is recommended as an effective anti-malarial by international health agencies, including the World Health Organisation. Ministry of Defence (MOD) and the National Health Service both follow National Institute for Care and Excellence guidelines on the prescription and management of side effects associated with mefloquine.

The MOD is engaged with NHS England (NHSE) through the NHSE Armed Forces Clinical Reference Group. This group has recently reviewed the clinical management of the side effects associated with mefloquine. As symptoms can resemble acute psychiatric conditions, clinicians are advised to assess patients individually and are expected to take a full drug and alcohol history, including any previous mefloquine use.

In England, Op COURAGE and Op RESTORE provide a broad range of specialist mental health, physical and wellbeing care services to veterans, with similar services available in Scotland, Wales and Northern Ireland.

I would encourage any Veteran who is struggling with their mental health to self-refer or seek the support of their GP to access Op COURAGE, the Veterans' Mental Health and Wellbeing Service. The side effects that may be experienced whilst taking, or with a history of having taken mefloquine, will be treated according to the diagnosis; for example, if the patient is experiencing depressive symptoms, the treatment for depression will be instigated.

The Ministry of Defence is unable to disclose the total amount of damages paid out for common law claims related to Lariam as they are subject to the usual confidentiality undertaking agreed with claimants' legal representatives. The same applies to claimant legal costs.

The claimant's legal costs are the subject of negotiation between the parties, and it is hoped that they will be resolved soon. It is not currently possible to provide a timeline.

Damages have been settled in all 434 claims brought by Hilary Meredith Solicitors against the Ministry of Defence relating to the use of Lariam. The claimants' legal costs have still to be resolved.

The Ministry of Defence is not aware of any issues concerning missing medical records on the use of Lariam (mefloquine) by Armed Forces personnel. The Department can additionally confirm there are no outstanding requests for any medical records where a person believes they have been prescribed Lariam (mefloquine).

Hilary Meredith Solicitors and the Ministry of Defence agreed to the inclusion of a confidentiality clause in the court order covering the damages settlement. It is a common feature of out of court settlements to keep confidential the amount of damages paid to claimants as well as the amount of legal costs paid to their solicitors.

The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for ensuring that medicines, medical devices, and blood components for transfusion meet applicable standards of safety, quality, and efficacy. The MHRA rigorously assesses the available data, including from the Yellow Card scheme, and seeks advice from the Commission on Human Medicines, the MHRA’s independent advisory committee, where appropriate, to inform regulatory decisions, including amending the product information.

Mefloquine, commercially known as Lariam, is effective in the prevention and treatment of malaria and is licensed for use by the MHRA in the United Kingdom. The current product information for mefloquine states that neuropsychiatric adverse reactions may occur during treatment and includes warnings and precautions to minimise these risks. It also states that such adverse reactions may persist for months, or longer, even after discontinuation of the drug. It has not been established, however, that such adverse reactions may be permanent.

Patient safety is our top priority, and no medicine would be approved unless it met our expected standards of safety, quality, and effectiveness. Our role is to continually monitor the safety of medicines during their use, including Larium. We have robust, safety monitoring and surveillance systems in place for all healthcare products.  When a safety issue is confirmed, we always act promptly to inform patients and healthcare professionals and take appropriate steps to mitigate any identified risk.

As with any medicine, clinicians are responsible for making prescribing decisions for their patients, taking into account best prescribing practice and the local commissioning decisions of their respective integrated care board.

Clinicians are also expected to take account of appropriate national guidance on clinical effectiveness and safety, and are accountable for their prescribing decisions, both professionally and to their service commissioners. The national guidance for mefloquine is available at the following link:

https://cks.nice.org.uk/topics/malaria-prophylaxis/prescribing-information/mefloquine/

Prescribers are responsible for ensuring that any side effects experienced by their patients are addressed promptly, they should work with their patient to decide on the most suitable management plan, with the provision of the most clinically appropriate care for the individual always being the primary consideration.

The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for ensuring that medicines, medical devices, and blood components for transfusion meet applicable standards of safety, quality, and efficacy. The MHRA rigorously assesses the available data, including from the Yellow Card scheme, and seeks advice from the Commission on Human Medicines, the MHRA’s independent advisory committee, where appropriate, to inform regulatory decisions, including amending the product information.

Mefloquine, commercially known as Lariam, is effective in the prevention and treatment of malaria, and is licensed for use by the MHRA in the United Kingdom. The current product information for mefloquine states that neuropsychiatric adverse reactions may occur during treatment, and includes warnings and precautions to minimise these risks. It also states that such adverse reactions may persist for months, or longer, even after discontinuation of the drug. It has not been established, however, that such adverse reactions may be permanent.

Patient safety is our top priority, and no medicine would be approved unless it met our expected standards of safety, quality, and effectiveness. Our role is to continually monitor the safety of medicines during their use, including Larium. We have robust, safety monitoring and surveillance systems in place for all healthcare products.  When a safety issue is confirmed, we always act promptly to inform patients and healthcare professionals and take appropriate steps to mitigate any identified risk.

People taking mefloquine (also known as Larium) can experience abnormal dreams, symptoms of depression and anxiety, and more rarely psychiatric symptoms such as hallucinations, agitations and psychosis have also been reported. This differs to Post Traumatic Stress Disorder (PTSD) where very specific criteria must be met to establish a diagnosis. Essential to this diagnosis is that the individual will have been exposed to an extremely threatening or horrific event or a series of events.

Given the specifics required for the diagnosis of PTSD, is it unlikely for those presenting with any side effects of taking mefloquine to be confused with that of PTSD.

The Ministry of Defence does not recognise the term ‘Larium toxicity’ however, the side effects that may be experienced whilst taking mefloquine will be treated according to the diagnosis; for example, if the patient is experiencing depressive symptoms, the treatment for depression will be instigated.

The information requested about the numbers of personnel discharged over the previous 10 years whilst experiencing symptoms related to taking mefloquine, is not held centrally and could be provided only at disproportionate cost.

The Department continues to monitor and publish bi-annual statistics on the number of prescriptions for mefloquine (also known as Larium) given to UK Armed Forces personnel at Ministry of Defence medical facilities since 12 September 2016.

The full release of information can be found at the following link:

https://www.gov.uk/government/collections/mefloquine-lariam-prescribing-in-the-uk-armed-forces-statistics-index

Mefloquine, commercially known as Lariam, is effective in the prevention and treatment of malaria and is licensed for use by the Medicines and Healthcare products Regulatory Agency (MHRA) in the United Kingdom. The current product information for mefloquine states that neuropsychiatric adverse reactions may occur during treatment and includes warnings and precautions to minimise these risks. It also states that such adverse reactions may persist for months, or longer, even after discontinuation of the drug. It has not been established, however, that such adverse reactions may be permanent.

The UK was involved in the European Union’s safety review in 2013 which concluded there was a need for additional measures to strengthen the existing safety warnings for neuropsychiatric effects. A range of regulatory actions were implemented in Europe and the UK, including a letter to healthcare professionals highlighting the strengthened warnings about psychiatric effects in the product information for mefloquine, prescribing guides and checklists for healthcare professionals, and an alert card for patients. These documents are available at the following link:

https://www.medicines.org.uk/emc/product/9670/smpc

An article highlighting the new advice was also published in the MHRA’s Drug Safety Update newsletter, which is available at the following link:

https://www.gov.uk/drug-safety-update/mefloquine-strengthened-warnings-on-neuropsychiatric-side-effects

Subsequently, in 2014, the mefloquine product information was revised to warn that some psychiatric reactions may occur after discontinuation of mefloquine and may persist for some time after discontinuation. These updates were implemented across Europe including in the UK. Annual reminder letters highlighting the main risks associated with mefloquine and the patient checklist and alert card were issued until 2021 after which time it was agreed that due to low use of the product and a lack of enquiries for the risk minimisation materials annual letters were no longer required. The patient checklist and alert card remain available in the UK.

As with any medicine, clinicians are responsible for making prescribing decisions for their patients, considering best prescribing practice and the local commissioning decisions of their respective integrated care boards (ICBs). They are also expected to take account of appropriate national guidance on clinical effectiveness and safety, and are accountable for their prescribing decisions, both professionally and to their service commissioners. Prescribers are responsible for ensuring that any side effects experienced by their patients are addressed promptly; they should work with their patient to decide on the most suitable management plan, with the provision of the most clinically appropriate care for the individual always being the primary consideration.

To date, 60 claims have been partially settled and three claims have been fully settled. Partially settled claims are those where damages have been agreed and paid to a Claimant, but where the Claimant's solicitor's costs remain in dispute.

A total of 457 claims are the subject of continuing legal action, in that they have not yet been resolved.

A trial has been listed for March 2025 to establish generic issues. At this trial 10 lead cases from the largest Claimant cohort will be heard. The trial means that all other claims are stayed until the outcome of the lead cases is decided.

The Department has been notified of a total of 686 common law claims relating to the alleged adverse effects of Lariam. A breakdown of claims in each of the last three years is not readily available, however, most the claims were notified prior to April 2021. The Ministry of Defence continues to resolve claims wherever possible.

Anti-malaria drugs, including mefloquine, are only prescribed after a face-to-face individual risk assessment and mefloquine is only prescribed by a doctor and after other alternatives have been identified as unsuitable.

Personnel supplied with anti-malarial drugs, including mefloquine, are issued copies of all manufacturer-provided patient documentation relevant to that drug and are informed of all special warnings or precautions to anti-malarial drugs.

All personnel receive a pre-deployment brief in accordance with Joint Service Publication (JSP) 950 leaflet 3-2-2 'Operational Deployment Health Briefings'. A key area covered by the brief is a description of the anti-malaria drugs including information about dosing and side effects at an appropriate level for the audience, tailored to the specific operation or exercise.

There is additional guidance to individuals outlined in Joint Service Publication 950 Leaflet 3-3-1: Preventing Malaria in Military Populations.