These notes are for guidance only - hillwalkers are advised to attend a Mountain First Aid course [Search]. These notes are copyright © Ian Roy, 1991 and are reproduced here with permission from Boots Across Scotland. I have tried to stay as close as possible to the original text adding only where I thought appropriate. Please also read our disclaimer.

by Ian Roy

[General] [Dehydration] [Over Exertion] [Heat Exhaustion] [Heat Cramps] [Heat Stroke]


Doing too much, too quickly, for too long!

Inevitably you will someday come across a walker suffering Fatigue, Dehydration (and salt depletion) and apparent lack of motivation to continue. They will be: Exhausted - Thirsty - Fed Up.

INDICATIONS that someone in your party is starting to suffer could be:

  • Slowing Down
  • Gasping for air
  • Feeling Weak
  • Feeling Dizzy
  • Feeling or being Sick
  • Possible Headache

If a member of your party is feeling like this (or you suspect that they are) then there are some important QUESTIONS TO BE ASKED:

What have you eaten today?
Carbohydrates are the most important, Fats then Proteins.

Think about what food you're intending to take... how long will you be out? how strenuous the day? How much do you normally eat? Sandwiches are good but it can often be best to avoid hard to digest foods like thick cheese. Fruit is great and many people swear by mini Mars Bars or Kendal Mint Cake - whatever you decide, make sure you have enough and remember to eat and drink "Little & Often". Remember that what you eat the day before also affects your energy supplies!

How much liquid have you drunk today?
"Steaming along" means you need water - even a short day in the hills requires at least 1 pint! (0.6L)

When deciding what/how much liquid to take this should always be considered alongside your food. Plain-old-water is usually the best but oranges or similar fruits are a good source of fluid, too. Fizzy/very acidic drinks are not necessarily the best thing to take but are better than nothing. For a normal day in the hills it is usually recommended that you take at least 2 litres of fluid with you.

Have you had any salt?
Salt lost in perspiration (sweat) needs to be replaced either by 1 or 2 salt tablets or in the food.

This can be in crisps for example or in sandwich fillings but if you're unsure you should check before you set out.

Have you done this sort of thing recently?
Are you physically fit enough for what you're attempting?
The answers to these two question go together each with leading to fairly obvious inferences...

If the answer is "No" to even one question then you should: SIT - REST - DRINK - EAT.

Ideally the affected party should take/be given a warm, salted sugary drink. At least 1-2 cupfuls.

1/2 teaspoon SALT + 1 teaspoon SUGAR + 0.6 L Water
(+ 1/2 teaspoon of Baking Soda for WHO rehydration recipie)

Fresh fruit juice or a stock cube/OXO/Bovril are also ideal.

Nine times out of ten the person is likely to feel much better withing 10-15 minutes and are lileky to be raring to go providing they were keen to start with!


Inadequate Food Consumption
Up to 4000 calories a day are needed for long, strenuous activity. (That's equivalent to about 50 biscuits or 3.5 loaves of bread!).

A good mix of foodstuffs is also required - this should be about 60% Carbohydrates, 20% Fats and 20% Proteins.

You should make the effort to eat the fats and proteins the previous evening and in the morning before you start out. This shouldn't be interpreted as meaning that a greasy bacon sandwich is ideal preparation for a day in the hills... possibly better would be pizza/pasta /potatoes with meat/veg/cheese the night before and cereals (porridge?) with whole milk at breakfast.

Dehydration and Salt Deficiency
Muscle energy activity produces heat. Generally speaking the body needs to lose this heat and it's mechanism for this is the combination of Perspiration (sweat) and Evapouration (breath and of sweat). On a typical day in the mountain you can expect the amount of fluid your body may lose to be measurable in pints! (1 pint = 0.55L) and possibly as much as 2-3 litres (or more in extreme cases).

The weather does not have to be hot/sunny - your body will attempt to lose heat like this even if it's cold and windy.

More Water comes out than goes in is generally what happens: - this can upset the chemical balance of your body and can result in possible collapse. It also increases the chances of suffering clinical shock if you sustain a minor injury. The indications of dehydration/salt depletion are:

  • Feeling Tired
  • Feeling Weak
  • Feeling Dizzy
  • Feeling/Being Sick
  • Possible Headache
  • Thirsty and dry/sore throat
  • Muscle cramps (limbs - esp legs/ stomach)


Eat & Drink "Little and Often" - 1 or 2 cups of fluid per hour and equivalent of about 2 salt tablets per day. Stop and rest for at least 5 minutes in every hour for a drink (and a snack).


1-2 cupfuls of a warm, salter, sugary drink (as above).


Physical exhaustion to the point of collapse is usually combined with dehydration and salt depletion as described above.

The persons exhaustion is likely to be Mental as well as Physical and they are likely to show a lack of interest or even detachment.

It is possible that a person with such symptoms could be a danger to themselves and to the group. They are more likely to sustain/suffer

  • General Injuries
  • Hypothermia
  • Cold damage


  • Stop immediately and rest.
  • Drink and comsume food (slowly) to replace fluid, salt and carbohydrates.
  • Shelter from Wind/Rain
At this point you should discuss and decide how you are to get the person off the hill or whether they will require rescued.


This is likely to occur when someone is either:

  • Exposed to a hot environment OR
  • Overheated through physical exertion

The air temperature does not need to be high nor does it need to be sunny for this to happen.

Blood vessels in te skin dilate and become full of blood. This is the body desperately trying to lose heat by moving as much blood as close to the surface of the skin as possible. The side effect of this is that blood is diverted away from the brain and possibly from other vital organs. The result of this can be an inadequate blood supply to the brain which can make the person feel faint or cause unconciousness.

The chances of suffering heat exhaustion are greatly increased if the person is suffering (even slightly) from dehydration or salt deficiency through perspiration.

INDICATIONS that a member of your party could be suffering heat exhaustion.

  • Feeling Tired
  • Feeling Weak
  • Feeling Dizzy
  • Feeling/Being Sick
  • Possible Headache
  • Feeling very Thirsty (then loss of thirst)
  • Restless
  • Pale complexion
  • Profuse sweating
  • Temperature about normal or slightly lower


Lie the person down and shelter them from the sun. Try to keep them cool. Treat for dehydration/salt depletion immediately.

Recovery is usually quite quick if the symptoms are identified and treated quickly.

Most often this is manifested as muscle spasms in the stomach or libs (normally the legs). It is caused by:
  • Salt deficiency from prolonged sweating
  • Lactic acid collecting in muscle tissue
  • Shortage of salt or water due to physical activity.
  • Lie down and Rest.
  • Stretch the muscle carefully, or if it is the back of a leg, press thumb firmly into centre of muscle for ten seconds or so, then release.
  • Treat for dehydration/salt depletion.
  • Drink some more and gently massage the muscle for a few minutes before continuing.

This is an extremely dangerous condition.

Symptoms: sweating stops and the body's termperature control breaks down resulting in high body temperature (>105 F / 40°C).

Aged, overweight or alcoholic persons are particularly susceptible to this condition.

  • Face is Hot, Flushed, Dry
  • Dizzyness
  • Headache
  • Restlessness
  • Pulse is string and bounding
  • Breathing is possibly heavy
  • Unconciousness - may be quick and deep.
  • CONSCIOUS: Lie the casualty down - head and shoulders raised and supported.
  • UNCONSCIOUS: Put casualty in recovery position.
  • Loosen or remove clothing.
  • Sponge down starting from head, or apply cold pads to forehead, arms, thighs, knees.
  • Shade from sun - fan to cool.
  • When the casualty's temperature falls, cover lightly with dry clothing.
  • Arrange evacuation from hill and urgent medical help.