The Met Office has issued a rare amber heat warning for Monday and Tuesday across parts of Wales and South England, urging the general population to prepare for symptoms and vulnerable individuals to take extra precautions. Two widely used prescription drugs—beta blockers and metformin—have been flagged as particular concerns during the heatwave, as they can heighten dehydration risk, disrupt temperature regulation, or mask warning signs of heat-related illness.
Beta Blockers and Heart Medications
According to the British Heart Foundation, beta blockers are among the most frequently prescribed treatments for heart and circulatory conditions, commonly used to manage irregular heart rhythms, angina, and elevated blood pressure. By reducing heart rate, this medication can compromise the body's natural cooling mechanisms, leaving those who take it far more susceptible to overheating.
The Medicines and Healthcare products Regulatory Agency (MHRA) has cautioned: "Blood pressure medicines such as ACE inhibitors, beta-blockers, or calcium channel blockers can also make it harder for your body to regulate temperature, especially during sudden hot spells." Research from 2022 also revealed that people taking beta blockers or antiplatelet drugs could face heightened risk of heart attacks during warm weather compared to milder temperatures. Beta blockers in particular showed a 65% stronger link between hot conditions and cardiac events.
Metformin and Diabetes Treatments
Metformin, insulin, and other diabetes treatments can elevate dehydration risk while concealing initial warning signs. Left unaddressed, dehydration can trigger deteriorating symptoms and, in severe instances, may result in kidney and urinary complications, seizures, or even brain injury. Important symptoms of dehydration include: feeling thirsty, headache and light-headedness, dark yellow strong-smelling urine, urinating less often, dizziness, tiredness, dry mouth and lips, and sunken eyes. Dehydration can be straightforward to remedy by consuming fluids or through oral rehydration solutions available from pharmacists.
Precautions and Advice
Those using beta blockers or metformin should not discontinue their treatment simply because temperatures are rising. Nevertheless, they should respond promptly if they begin experiencing any indicators of dehydration or heat-related illness symptoms. Anyone aged over 75 already faces greater vulnerability to temperature-related conditions including heat stroke, heat exhaustion, and dehydration. Relatives are urged to monitor elderly family members throughout periods of hot weather, particularly if they are taking these medicines.
The MHRA has advised anyone taking medication to consult their patient information leaflet or speak to their pharmacist to check whether sun sensitivity is listed as a potential side effect. The Met Office's amber warning for extreme heat runs from 1am on Monday 22 June through to 23:59pm on Tuesday 23 June. It marks the most severe heat warning the Met Office has issued in four years, with the previous one having been put out in August 2022. Authorities have warned of a "widespread impact" on both the public and infrastructure, cautioning that some workers may need to alter their schedules during this period. The warning further states: "The wider population are likely to experience some adverse health effects including sunburn or heat exhaustion and other heat related illnesses."
