A pharmacist with over 35 years of experience has issued urgent advice about 10 medicines that may affect how your body copes with hot weather. A yellow heat health alert was recently in place for parts of the UK, ending on July 17, but temperatures could reach 38°C next week.
Medicines That Affect Sweating and Hydration
Pharmacist Raj Patel, sharing advice with his 95,000 TikTok followers, listed the following medicines: olanzapine, quetiapine, chlorpromazine, oxybutynin, amitriptyline, bisoprolol, lithium, sertraline, methylphenidate, and furosemide.
Patel explained: “These medicines do not necessarily make you hotter. But they may interfere with the warning systems your body uses to cope with heat – making overheating, dehydration or heat exhaustion harder to recognise.”
How Each Medicine Affects Heat Response
Olanzapine, quetiapine, and chlorpromazine are antipsychotics that can interfere with the body’s temperature-control systems. Oxybutynin and amitriptyline have anticholinergic effects, reducing sweating and making it harder for the body to release heat.
Bisoprolol, a beta-blocker, slows heart rate and may reduce normal cardiovascular responses to heat. Lithium requires particular care because dehydration can increase lithium levels and raise toxicity risk. Sertraline may affect sweating and fluid balance. Methylphenidate can increase heart rate, reduce appetite, and make dehydration easier during prolonged activity. Furosemide, a water tablet, increases urine production and may contribute to dehydration, low blood pressure, and dizziness.
Higher Risk Groups
Patel noted that personal risk is higher for those over 65, with heart or kidney problems, diabetes, taking several medicines, struggling with dizziness or falls, exercising or standing outside for hours, drinking alcohol in the heat, experiencing vomiting or diarrhoea, or told to restrict fluids.
He emphasised: “Do not stop any prescribed medicine because you have seen it on this list. Stopping medicines such as beta-blockers, antidepressants, antipsychotics or lithium without clinical advice can be harmful.”
Advice for Staying Safe
Instead of drastic measures, Patel advises carrying water, taking regular shade breaks, avoiding the hottest part of the day (12pm–3pm), wearing light clothing, limiting alcohol, and keeping medicine out of direct sunlight.
He concluded: “The important point is not to panic. It is to understand how your medicines may change the way your body responds to heat. After 35 years as a pharmacist, I have learned that people often wait for dramatic warning signs. But heat illness can creep up quietly. Stay ahead of it.”
