Five common medicines that could be 'dangerous' in hot weather. Doctors warn of a 'perfect storm' of side effects for those on certain prescriptions. By Andrew Nuttall, Lifestyle Writer. 13:33, 12 Jun 2026.
Certain drugs can increase the risk of dehydration and interfere with temperature regulation. Temperatures in the UK could climb back above 30°C as warm weather returns this weekend. With the forecast in mind, doctors are urging people on certain medications to take care.
Weather Forecast
The Met Office is forecasting a break from the recent wet spell, with conditions on the way that will feel "notably warmer." Met Office deputy chief meteorologist Greg Wolverson said that approaching "high pressure" is likely to deliver "a drier and warmer weekend for many."
He said: "Saturday will see a more settled day of weather across southern areas, with some sunny spells developing. Temperatures here could reach 22-23°C. Northern areas may still see some cloud and occasional rain early on, but conditions are expected to improve here too later in the day.
"Sunday looks set to be widely dry across the UK, with further sunshine and temperatures continuing to rise. Many western parts of the UK can expect maximum temperatures in the low 20s, with the warmest spots likely across southern England where temperatures may reach 23-24°C, bringing a notably warmer feel compared to earlier in the week."
Met Office spokesman Dan Stroud also said earlier this week that the south and southeast of England are due for the highest temperatures over the weekend. He said there is "definitely a chance" of going above 30°C, "more so on Monday."
Doctor's Warning
GP Dr Hugh Coyne has warned that taking certain medications during hot weather can trigger a 'perfect storm' of unwelcome and sometimes dangerous side effects. He said: "Several commonly prescribed medications can make it harder for the body to cope with hot weather."
Taking certain medications in hot weather can create a 'perfect storm' of unwelcome and sometimes dangerous side effects.
Medications to be aware of include:
- Anticholinergic drugs: "Some bladder medications and older antihistamines can reduce sweating, which is one of the body's main cooling mechanisms," explains Dr Coyne.
- Antipsychotics and lithium: This type of medication "can affect the hypothalamus, the brain's temperature-control centre," says Dr Coyne.
- Beta-blockers and calcium channel blockers: Commonly prescribed for anxiety and heart problems, these medications "can limit the body's ability to move heat to the skin surface."
- Diuretics: Prescribed for a wide range of issues, from heart failure to kidney disease, diuretics "can also increase the risk of dehydration at a time when fluid balance is especially important."
- Antidepressants and SSRIs: Used to treat depression and anxiety, as well as other conditions, this medication "can affect the pathways involved in thermoregulation."
Taking just one of these medications can make it harder to regulate your temperature in the heat and lead to conditions like heatstroke. However, Dr Coyne, co-founder of Coyne Medical, a Private GP and Health Screening Clinic, says the "greatest concern is often in people taking more than one of these medications, as the effects can be cumulative."
He said: "Heatwaves can create a 'perfect storm' for some patients. Dehydration can cause medications such as lithium and digoxin to reach potentially toxic levels in the bloodstream, even when doses haven't changed.
"It's also worth noting that the strongest evidence for impaired temperature regulation relates to medications with a high anticholinergic burden, anti-Parkinson's drugs and non-selective beta-blockers." He adds that the evidence that antidepressants and antipsychotics are linked to heat intolerance is generally less robust.
People who take more than one of the medications listed have an increased risk of side effects.
Dr Coyne said that research indicates people taking psychiatric or cardiovascular medications face roughly double the risk of heat-related illness and death during extreme heat. Both physiological and behavioural factors are understood to contribute to this heightened risk.
What should you do this weekend if you're taking any of these medications?
"The key message is not to stop or alter prescribed medication without medical advice," Dr Coyne says. "Suddenly discontinuing treatment can carry significant health risks.
"Instead, focus on staying cool and well hydrated. Avoid prolonged exposure to the sun during the hottest part of the day, seek cooler indoor environments where possible, and drink fluids regularly rather than waiting until you feel thirsty."
Article continues below. For further guidance on managing dehydration, visit the NHS website's dedicated page. Call 999 or go to A&E if you or somebody else has signs of shock, which is a serious complication of dehydration.
