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Hot weather can have a serious impact on your health if proper care isn’t taken. With above-average temperatures forecast to continue through this summer[1], it’s important to take the risk of hot weather seriously.

People often use the term ‘heatstroke’ when they’ve actually experienced heat exhaustion, much like how a bad cold is sometimes described as ‘the flu’. While these terms are frequently used interchangeably, they describe very different conditions. Heat exhaustion is serious and, if left untreated, can develop into heatstroke, which can be life-threatening.

Who’s at risk during hot weather?

Overheating is a hazard for anyone, but some people are at higher risk because their age, medical conditions, or medication make it harder to regulate body temperature.

Those who are especially at risk include:

  • babies and young children, due to their small body and because their sweat glands are less developed
  • older adults, as our natural cooling mechanisms weaken with age
  • people taking medications that can affect body temperature, sweating, concentration, urine production, and blood flow
  • anyone who has a cardiac (heart) or respiratory (breathing) condition
  • vulnerable people, such as people with a learning disability, dementia, addiction, or serious mental health problems, who may not be alert to the risks of hot weather
“Within the Respiratory Service, we’ve seen extreme heat cause increased wheezing and higher risk of infections, therefore leading to requiring antibiotics and, in some cases, a stay in hospital.”
Carly Bloomfield, Cardiac Respiratory Nurse

If you think your prescribed medication might increase your risk of overheating, please speak to your GP or a pharmacist for advice. Do not stop taking your prescribed medication.

Having a physical or outdoors job or choosing to do demanding exercise or activities (such as DIY), can be dangerous in very hot conditions, even if you don’t fit into any of the above categories.

“One of the most common issues I have observed is that patients often feel unwell during periods of hot weather because they choose to exercise or spend time outdoors during the hottest part of the day, when temperatures are at their highest.”
Fiona Pennington, Cardiac Rehabilitation Exercise Instructor

The differences between heat exhaustion and heatstroke

Heat exhaustion is when you have a temperature over 38°C and lose too much water, leading to symptoms such as being very thirsty, dizziness, headache, muscle cramps, loss of appetite, and feeling sick.

A key sign that heat exhaustion has developed into heatstroke is that you stop sweating. If you’re already less able to sweat (due to age, medication, or a medical condition), you’re more vulnerable as your temperature can rise faster.

Having a temperature over 40°C and being unable to cool down is when heat exhaustion becomes heatstroke.

Symptoms of heatstroke include:

  • hot skin that isn’t sweating and might look red (this can be harder to see on brown and black skin)
  • rapid heartbeat
  • shortness of breath
  • confusion
  • a seizure or fit
  • loss of consciousness
  • symptoms of heat exhaustion that don’t improve despite efforts to rehydrate and cool down for 30 minutes

If you suspect someone has heatstroke, call 999. Heatstroke is a medical emergency as it can lead to brain damage, organ failure, and even death.

While you wait for assistance, put them in the recovery position if they have lost consciousness, and continue efforts to cool them down.

If you need advice quickly, but it’s not an emergency situation, contact 111.

How to avoid heat exhaustion and heatstroke

We asked clinicians from our Cardiac and Respiratory Specialist Services (CARSS), whose patients are at high risk during a heatwave, for some tips to help prevent illness during hot weather.

  • Look out for weather alerts from trustworthy sources, such as the Met Office, so that you can be prepared.
  • Drink enough water to replace the fluids you lose through sweating.
  • Avoid drinks that increase fluid loss through urination (known as diuretics), such as alcohol, coffee, and sugary drinks, or alternate with a glass of water.
  • Eat lighter meals with water-rich foods and avoid greasy and spicy foods that are harder to digest.
  • Stay out of direct sunlight, particularly from 11am to 3pm and especially if you take medications which react to UV radiation, such as some antibiotics, ibuprofen, antihistamines, and drugs prescribed for cardiovascular issues, such as statins.
  • Wear loose fitting clothing and, when outdoors, cover your head with a hat.
  • Limit the rising temperature in south-facing rooms by closing windows and curtains or blinds when it’s hotter outside than indoors.
  • Exercise during cooler parts of the day and avoid extreme workouts.
  • Apply suncream to prevent sunburn.
  • Use ice packs on your groin, armpits, and neck to cool down.

If you have a respiratory condition, keep your blue reliever inhaler (if prescribed) close to hand, and alert others when you feel your condition changes as it can decline quickly.

Further information

Find more advice about managing your health in a heatwave on our advice page:

[1] ‘More heatwaves likely as warmer-than-normal summer forecast’ (3 June 2026; Updated 10 June 2026), BBC News [Accessed 13 July 2026]