Wilderness Survival Medicine
(Adapted from the U.S. Army Survival Manual)
To survive, you need water and food. You must also have and
apply high personal hygiene standards. This page will cover basic
health issues, and then the survival medicine topic will continue
on the page Wilderness Survival
- Medical Emergencies.
Note: For water procurement tips, see the page Wilderness
Survival - Water.
Your body loses water through sweating, urinating, and defecating.
During average daily exertion when the atmospheric temperature
is 20 degrees Celsius (C) (68 degrees Fahrenheit), the average
adult loses and therefore requires 2 to 3 liters of water daily.
Cold exposure, intense activity, high altitude, burns, or illness,
can cause your body to lose more water. You must replace this
Dehydration decreases your efficiency and, if injured, increases
your susceptibility to severe shock. Consider the following results
of body fluid loss:
A 5 percent loss of body fluids results in thirst, irritability,
nausea, and weakness.
A 10 percent loss results in dizziness, headache, inability
to walk, and a tingling sensation in the limbs.
A 15 percent loss results in dim vision, painful urination,
swollen tongue, deafness, and a numb feeling in the skin.
A loss greater than 15 percent of body fluids may result in
Common signs and symptoms of dehydration are:
Dark urine with a very strong odor.
Low urine output.
Dark, sunken eyes.
Loss of skin elasticity.
Delayed capillary refill in fingernail beds.
Trench line down center of tongue.
Thirst. Last on the list because you are already 2 percent dehydrated
by the time you crave fluids.
Trying to make up a deficit is difficult in a survival situation,
and thirst is not a sign of how much water you need. Most people
cannot comfortably drink more than 1 liter of water at a time.
So, even when not thirsty, drink small amounts of water at regular
intervals each hour to prevent dehydration.
If you are under physical and mental stress or subject to
severe conditions, increase your water intake. Drink enough liquids
to maintain a urine output of at least 0.5 liter every 24 hours.
In any situation where food intake is low, drink 6 to 8 liters
of water per day. In an extreme climate, especially an arid one,
the average person can lose 2.5 to 3.5 liters of water per hour.
In this type of climate, you should drink 14 to 30 liters of
water per day.
With the loss of water there is also a loss of electrolytes
(body salts). The average diet can usually keep up with these
losses but in an extreme situation or illness, additional sources
need to be provided. A mixture of 0.25 teaspoon of salt to 1
liter of water will provide a concentration that the body tissues
can readily absorb.
Of all the physical problems encountered in a survival situation,
the loss of water is the most preventable. The following are
basic guidelines for the prevention of dehydration:
Always drink water when eating. Water is used and consumed
as a part of the digestion process and can lead to dehydration.
Acclimatize. The body performs more efficiently in extreme
conditions when acclimatized.
Conserve sweat not water. Limit sweat-producing activities but
Ration water. Until you find a suitable source, ration your
water sensibly. A daily intake of 500 cubic centimeter (0.5 liter)
of a sugar-water mixture (2 teaspoons per liter) will suffice
to prevent severe dehydration for at least a week, provided you
keep water losses to a minimum by limiting activity and heat
gain or loss.
You can estimate fluid loss by several means. A standard field
dressing holds about 0.25 liter (one-fourth canteen) of blood.
A soaked T-shirt holds 0.5 to 0.75 liter.
You can also use the pulse and breathing rate to estimate
fluid loss. Use the following as a guide:
With a 0.75 liter loss the wrist pulse rate will be under
100 beats per minute and the breathing rate 12 to 20 breaths
With a 0.75 to 1.5 liter loss the pulse rate will be 100 to
120 beats per minute and 20 to 30 breaths per minute.
With a 1.5 to 2 liter loss the pulse rate will be 120 to 140
beats per minute and 30 to 40 breaths per minute. Vital signs
above these rates require more advanced care.
Although you can live weeks without food, you need an adequate
amount to stay healthy. Without food your mental and physical
capabilities will deteriorate rapidly, and you will become weak.
Food replenishes the substances that your body burns and provides
energy. It provides vitamins, minerals, salts, and other elements
essential to good health. Possibly more important, it helps morale.
The two basic sources of food are plants and animals (including
fish). In varying degrees both provide the calories, carbohydrates,
fats, and proteins needed for normal daily body functions.
Calories are a measure of heat and potential energy. The average
person needs 2,000 calories per day to function at a minimum
level. An adequate amount of carbohydrates, fats, and proteins
without an adequate caloric intake will lead to starvation and
cannibalism of the bodys own tissue for energy.
Note: For more on plant foods, see the pages Edible
Wild Plants and Edible
Wild Berries, as well as Survival
These foods provide carbohydrates-the main source of energy.
Many plants provide enough protein to keep the body at normal
efficiency. Although plants may not provide a balanced diet,
they will sustain you even in the arctic, where meats heat-producing
qualities are normally essential. Many plant foods such as nuts
and seeds will give you enough protein and oils for normal efficiency.
Roots, green vegetables, and plant food containing natural sugar
will provide calories and carbohydrates that give the body natural
You can dry plants by wind, air, sun, or fire. This retards
spoilage so that you can store or carry the plant food with you
to use when needed.
Meat is more nourishing than plant food. In fact, it may even
be more readily available in some places. However, to get meat,
you need to know the habits of, and how to capture, the various
To satisfy your immediate food needs, first seek the more
abundant and more easily obtained wildlife, such as insects,
crustaceans, mollusks, fish, and reptiles. These can satisfy
your immediate hunger while you are preparing traps and snares
for larger game.
In any situation, cleanliness is an important factor in preventing
infection and disease. It becomes even more important in a survival
situation. Poor hygiene can reduce your chances of survival.
Pay special attention to the feet, armpits, crotch, hands, and
hair as these are prime areas for infestation and infection.
If water is scarce, take an "air" bath. Remove your
clothing and expose your body to the sun and air for an hour.
Be careful not to sunburn. If you dont have soap, you can
use ashes or sand.
Keep Your Hands Clean
Germs on your hands can infect food and wounds. Wash your
hands after handling any material that is likely to carry germs,
after visiting the latrine, after caring for the sick, and before
handling any food, food utensils, or drinking water. Keep your
fingernails closely trimmed and clean, and keep your fingers
out of your mouth.
Keep Your Hair Clean
Your hair can become a haven for bacteria or fleas, lice,
and other parasites. Keeping your hair clean, combed, and trimmed
helps you avoid this danger.
Keep Your Clothing Clean
Keep your clothing and bedding as clean as possible to reduce
the chance of skin infection as well as to decrease the danger
of parasitic infestation. Clean your outer clothing whenever
it becomes soiled. Wear clean underclothing and socks each day.
If water is scarce, "air" clean your clothing by shaking,
airing, and sunning it for 2 hours. If you are using a sleeping
bag, turn it inside out after each use, fluff it, and air it.
Keep Your Teeth Clean
Thoroughly clean your mouth and teeth with a toothbrush at
least once each day. If you dont have a toothbrush, make
a chewing stick. Find a twig about 1 centimeter wide. Chew one
end to separate the fibers. Now brush your teeth thoroughly.
Another way is to wrap a clean strip of cloth around your fingers
and rub your teeth with it to wipe away food particles. You can
also brush your teeth with small amounts of baking soda, salt,
or soap. Then rinse your mouth with water, salt water, or willow
bark tea. Also, flossing your teeth with string or fiber helps
If you have cavities, you can make temporary fillings by placing
candle wax, tobacco, aspirin, hot pepper, tooth paste or powder,
or portions of a ginger root into the cavity. Make sure you clean
the cavity by rinsing or picking the particles out of the cavity
before placing a filling in the cavity.
Take Care of Your Feet
Wash and massage your feet daily. Trim your toenails straight
across. Wear an insole and the proper size of dry socks. Powder
and check your feet daily for blisters.
If you get a small blister, do not open it. An intact blister
is safe from infection. Apply a padding material around the blister
to relieve pressure and reduce friction. If the blister bursts,
treat it as an open wound. Clean and dress it daily and pad around
it. Leave large blisters intact. To avoid having the blister
burst or tear under pressure and cause a painful and open sore,
do the following:
Obtain a sewing-type needle and a clean or sterilized thread.
Run the needle and thread through the blister after cleaning
Detach the needle and leave both ends of the thread hanging out
of the blister. The thread will absorb the liquid inside. This
reduces the size of the hole and ensures that the hole does not
Pad around the blister.
Get Sufficient Rest
You need a certain amount of rest to keep going. Plan for
regular rest periods of at least 10 minutes per hour during your
daily activities. Learn to make yourself comfortable under less
than ideal conditions. A change from mental to physical activity
or vice versa can be refreshing when time or situation does not
permit total relaxation.
Keep Camp Site Clean
Do not soil the ground in the camp site area with urine or
feces. Use latrines, if available. When latrines are not available,
dig "cat holes" and cover the waste. Collect drinking
water upstream from the camp site. Purify all water.
Steve's Notes: Avoid getting too tired. Fatigue
is one of the biggest reasons for injuries. Travel on level ground
when fatigued may be safe, but don't climb steep trails or travel
over rocky terrain until you are rested (unless you have no choice,
Continues here: Wilderness
Survival - Medical Emergencies.
Back to the Wilderness