Heat exhaustion and heat stroke - too much of a good thing

Most of us welcome the coming of spring with relief, especially after a grey, cold winter. Across most of the world, sun is something we look forward to - there's a multi-billion dollar travel industry that relies on our love of sun, sea and sand.

But it wasn't always that way, even in the decidedly non-tropical UK. Until only a couple of hundred years ago, nobody would dream of exposing themselves to the sun by choice. Women painted and powdered their skins to look as white as possible. Being pale and interesting meant you weren't forced to work outside as a manual labourer - you could afford to stay inside.

These days, if you can't get the real thing, there are sunbeds (very bad news healthwise) and artificial tans (a much safer alternative if you don't fancy the pale English rose look). But most of us bolt out into the sunshine the moment we can, often forgetting the very real risks of too much heat.

Heat exhaustion and heat stroke - who's at risk?

Anyone can suffer the physical effects of excess heat, but people at highest risk include:

  • Babies and toddlers
  • Elderly people
  • People who are physically active
  • People with chronic health conditions like diabetes or heart, lung or kidney disease
  • People taking diuretics or 'water tablets' (usually used for high blood pressure or heart failure), antipsychotic medication or recreational drugs like ecstasy
  • People with tummy troubles like gastroenteritis or inflammatory bowel conditions like Crohn's or ulcerative colitis that can cause diarrhoea.

Heat exhaustion

Remember homeostasis from your school biology lessons? Your body is very good at it - it means keeping your internal environment constant, regardless of what's going on outside. Like a finely tuned racing car, your body's internal processes work best when levels of water, body salts and temperature are just right.

So when you get hot, your body's protection mechanisms kick in. You sweat to lose heat; your urine becomes more concentrated to preserve water; and your body tells you that you need to drink more and get out of the sun.

If you stay in the heat, your body starts to struggle. If you want to find out how to avoid heat exhaustion, read my top tips.

Symptoms of heat exhaustion

Key signs and symptoms of heat exhaustion include:

Passing less urine (which is very dark)

  • Dizziness and feeling faint
  • Tiredness
  • Headache
  • Feeling sick, lack of appetite and cramping stomach pain
  • Muscle cramps in legs and arms
  • Rapid pulse
  • Clammy, pale skin and profuse sweating.

Treating heat exhaustion

Fluid and a cool environment are key to treating heat exhaustion. If you think you're showing signs, immediately:

  • Move to a cool room
  • Take off as much clothing as possible, particularly tight clothes
  • Take a cool bath or shower
  • If there are no bathing facilities, sponge down with cool water
  • Put on a fan if possible (if your skin is damp, the evaporation will cool you down quicker)
  • Lie down if possible
  • Drink as much non-alcoholic fluid as you can
  • Seek medical help if you're not feeling better within about half an hour.


Sunstroke is a form of heatstroke. The only different is that it's caused specifically by being exposed to too much direct sunlight. Symptoms and treatment are exactly the same as for heatstroke - they're both medical emergencies.

The only added issue is that there's a risk of severe sunburn on top of other complications. Blistering of the skin is a sign of severe sunburn - sponge the skin gently with cool clean water while waiting for medical help.

Heat stroke

In heat stroke, your body can no longer cope. The normal mechanisms to keep your body cool give up, and your temperature soars to over 40 degrees C. Other symptoms include:

  • Severe, throbbing headache
  • Feeling very sick and vomiting
  • Fast pulse (which can be weak or very strong and 'bounding' along)
  • Shallow, rapid breathing
  • Very hot, flushed skin
  • Weak or cramping muscles
  • No sweating despite being very hot
  • Dizziness, feeling faint or fainting
  • Confusion and agitation
  • Seizures
  • Sometimes collapse and loss of consciousness.

Treating heat stroke

Heat stroke is a medical emergency, and can cause serious damage to kidneys and other vital organs if not treated promptly. Someone suffering from heat stroke is unlikely to be able to treat themselves. If you think someone has heat stroke, immediately:

  • Dial 999. While waiting:
  • Move them to a cool place and lie them down
  • Stay with them at all times
  • Remove as much clothing as possible
  • Wet their skin with cool water, then fan them
  • If possible, put them in a cool bath or shower
  • For a young, healthy person who has developed heat stroke from vigorous exercise in hot weather, consider applying ice packs to armpits, neck and back
  • Put them in the recovery position if they lose consciousness.

Prevention, of course, is always better than cure - so do take steps to avoid getting heat stroke in the first place.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.