The Medicines and Healthcare products Regulatory Agency (MHRA) has issued urgent advice for individuals using insulin or prescribed metformin as the United Kingdom endures an extended amber heat health alert. The UK Health Security Agency (UKHSA) has prolonged the warning, which now covers multiple regions including London, the South West, South East, East and West Midlands, and the West of England.
Record-Breaking Temperatures
The UK has experienced record-breaking heat for late May, with temperatures reaching 35°C at Heathrow and Kew Gardens in London — the hottest May day on record for the second consecutive day. The amber alert, alongside yellow warnings for the North East and North West, will remain in effect until 5 PM on Thursday.
Health Risks for Vulnerable Groups
According to the UKHSA and Met Office's Weather-Health alerting system, an amber Heat Health alert indicates that impacts are likely to include increased demand on healthcare services from vulnerable groups. There is also a heightened health risk for those aged over 65 or living with pre-existing medical conditions.
Dr. Anya Gopfert, Consultant in Health Protection at UKHSA, stated: "We know that even moderate heat can lead to serious health problems, especially for older people and those with certain health conditions, so it's important that everyone takes simple precautions while enjoying the warm weather over the coming days." She added: "If you have friends, family or neighbours who are more vulnerable, it is important to check in on them and ensure they are aware of the forecasts and are following the necessary advice."
Medication Precautions
The MHRA is specifically cautioning those who use insulin or are prescribed metformin to exercise extreme care during warm weather. These medicines, used to manage diabetes, can heighten the risk of dehydration or make early warning signs harder to recognise. Additionally, antipsychotic medications such as olanzapine or quetiapine, or stimulant medications for attention disorders, can raise body temperature, making it easier to overheat.
Dehydration can trigger dizziness, headaches, fatigue, confusion, and dark urine — posing a particularly serious risk to older adults, young children, and those with heart or kidney conditions. Experts recommend that anyone who begins to feel unwell in the heat should move to a cooler location, sip water slowly, and seek medical advice if symptoms fail to improve promptly.
MHRA Chief Safety Officer's Advice
Alison Cave, Chief Safety Officer at the MHRA, said: "Let's face it – when there's a heatwave, most of us are focused on getting outside and enjoying it while it lasts. But it's easy to forget that medicines left in the heat – in cars, bags, or on sunny windowsills – might not work properly when you need them." She continued: "Some medicines can also make you more likely to burn in the sun, feel dizzy, or get dehydrated, especially if you're taking diuretics or have a condition like asthma, heart disease, or diabetes."
To stay safe in the heat, Cave advises: "Store medicines somewhere cool, dry and out of direct sunlight – especially if you're out and about. Know the signs of heat-related illness – stay hydrated and listen to your body. Take extra care in the sun if your medicine makes your skin more likely to burn. And remember, for all medicines it's important to read the leaflet and speak to a healthcare professional if you have any questions."
