Millions of people on beta blockers and metformin are being warned to take extra precautions as the Met Office issues a rare amber heat warning for parts of Wales and South England from Monday to Thursday.
The warning, in place for four days from 22 June, says the general population are likely to experience symptoms, but those classed as ‘vulnerable’ have been urged to act. That includes people taking two of the most widely prescribed medications in the UK: beta blockers and metformin.
“Millions on beta blockers and metformin face increased heat risks as amber warning issued for England and Wales.”
Beta blockers, used to treat heart conditions and high blood pressure, slow the heart rate and can affect the body’s ability to regulate temperature, making overheating more likely. The Medicines and Healthcare Products Regulatory Agency (MHRA) warns: “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.”
The British Heart Foundation says beta blockers are among the most common treatments for heart and circulatory conditions, prescribed for irregular heart rhythms, angina and lowering blood pressure. But a 2022 study found that people using beta blockers or antiplatelet medications could be more likely to have heart attacks during hot weather — with beta blockers specifically associated with a 65% increase in the link between hot weather and heart attacks.
Metformin, used to treat diabetes, along with insulin and other diabetes medications, can increase the risk of dehydration while masking early symptoms. If left untreated, dehydration can lead to kidney and urinary issues, seizures or even brain damage.
Experts warn that people should not stop taking their medication because of the heat, but should act quickly if they experience signs of dehydration or heat-related illness. Those over 75 are already at higher risk of heat stroke, heat exhaustion and dehydration, and families have been urged to check on loved ones.
The warning comes as London braces for temperatures of up to 38C, with the amber alert extended to at least Thursday. The heatwave has already caused problems at Hampstead Heath, where the City of London Corporation has issued a warning for the swimming ponds after fights broke out at the Parliament Hill Fields Lido and crowds of people entered non-swimming ponds during last month’s heatwave.