People on certain medications may need to take precautions and watch out for side effects in the heat15:13, 26 May 2026The May bank holiday weekend broke multiple records for being the hottest bank holiday on record, hottest May Day in the UK, the first time temperatures hit 30C this year and the first time it reached this point in May anywhere in the UK since 2012.‌For some, the sunny weather marks a welcome start to summer but many may not realise how it could affect their health, particularly their medication. Certain medications may disrupt the way your body handles heat, making you more susceptible to issues like dehydration, while extreme heat can also interfere with how your body absorbs and uses the medication itself in some cases.‌The Medicines and Healthcare products Regulatory Agency (MHRA) has issued an alert, highlighting the different types of medications that could be affected and reminding people how to avoid experiencing weather-related health issues while managing long-term conditions.‌MethotrexateThis medication is commonly used to treat a range of conditions from rheumatoid arthritis to psoriasis, Crohn’s disease and cancer. However, it also makes your skin extremely sensitive to the sun even at low doses.This can cause painful rashes, blistering, or swelling that looks like severe sunburn. MHRA noted: “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 number of other medications can cause your skin to become more sensitive to the sun, meaning it may burn easily even in mild sunlight. Some antibiotics, diuretics, antidepressants and skin treatments for acne or eczema can cause this.‌DiureticsDiuretics, also known as ‘water tablet’s like furosemide, are a group of medicines usually prescribed for heart conditions, it works by removing excess fluids from the body to control blood pressure. However, this directly increases the risk of dehydration and mineral imbalances during a heatwave and diuImportant symptoms of dehydration:‌feeling thirstyheadache and feeling light-headeddark yellow, strong-smelling peepeeing less often than usualfeeling dizzy or lightheadedfeeling tireda dry mouth, lips and tonguesunken eyesBlood pressure medicationACE inhibitors, beta-blockers, calcium channel blockers and other blood pressure medication can make it harder for your body to regulate temperature or even suppress your natural thirst response.Article continues belowDiabetesInsulin, metformin and other diabetes medication can increase the risk of dehydration while also making the early symptoms of dehydration harder to spot. Insulin can be absorbed more quickly from injection sites during warm weather which can also increase the risk of hypos according to Diabetes UK.Antipsychotic medicationOlanzapine or quetiapine, or stimulant medications for attention disorders can sometimes increase your body temperature. This could mean you overheat more easily when the temperatures start to climb.The MHRA urged people on any medications to read the patient information leaflet or check with their pharmacist to see if they may risk having a sun sensitivity as a side effect.