The recent May bank holiday shattered several weather records across the UK after temperatures reached 30°C for the first time this year. While many people welcome the glorious sunshine as the start of summer, the heat brings hidden hazards for those on regular medication. Medical professionals have warned that certain prescription treatments can interfere with the body's regulation of internal temperature or alter how medications are absorbed. The Medicines and Healthcare products Regulatory Agency (MHRA) has issued an official warning regarding various pharmaceutical categories. Experts want to help people avoid seasonal health complications while they manage ongoing illnesses.
Methotrexate and Sun Sensitivity
Methotrexate is widely prescribed by doctors to manage diverse ailments ranging from rheumatoid arthritis to cancer. However, the formulation also leaves the skin highly sensitive to natural sunlight. This specific reaction can quickly cause painful rashes, severe blistering, or swelling that looks identical to a serious burn. The MHRA says: "In rare cases, these reactions have led to serious infections... Even a short walk at lunchtime or a train ride in the sun can be enough to trigger a reaction for some people." A variety of alternative treatments can also make your skin extra sensitive to UV rays. Common antibiotics, water tablets, antidepressants, and topical acne therapies are all known to trigger this exact vulnerability.
Diuretics and Dehydration Risk
Diuretics, frequently referred to as 'water tablets', such as furosemide, are routinely used to manage high blood pressure. They work by removing excess fluid from the body, which naturally increases the risk of dehydration during a heatwave. Symptoms of dehydration include: a dry mouth, lips and tongue; dark yellow, strong-smelling pee; feeling dizzy, thirsty, tired, or light-headed; headache; peeing less often than usual; and sunken eyes.
Blood Pressure Medication and Temperature Regulation
Treatments like ACE inhibitors and beta-blockers can make it much harder for your system to control its own temperature. These everyday heart pills can also suppress your natural thirst response when you need fluids most.
Diabetes Medications and Hypoglycemia
Standard insulin regimens and metformin pills can increase the risk of dehydration while masking the early warning signs of the condition. Insulin can also be absorbed much faster from injection sites during hot spells, which Diabetes UK warns can increase the risk of hypoglycemia (hypos).
Antipsychotic Medication and Overheating
Mental health treatments like olanzapine or stimulant formulas for attention disorders can occasionally raise your core body temperature. This means you might overheat much more quickly as summer weather intensifies.
Expert Advice
The MHRA has advised anyone taking medication to consult their patient information leaflet or speak with their pharmacist to determine whether sun sensitivity could be a potential side effect. Staying cool and hydrated is essential during hot weather, especially for those on these medications.
