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Hypothermia usually occurs when the body temperature falls below normal. The causes of it could be being out in the extreme cold that is added with wet clothes and wind chill.
Symptoms of it is drowsiness, a lowered heart rate and breathing, and unconsciousness.
Treat it very carefully , if you have no way to get medical help. In an emergency situation.
The number one priority is to raise the body temperature of the person evenly and gently.
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Get the person out of their wet clothing and replace it with dry clothing.
Place them in a sleeping bag in a warm area. Like, close to a campfire, etc. If you have to , get in the bag with the person so your body heat is helping raise theirs.
If you have the way to - get them in a warm bath.
If breathing stops perform CPR.
Seek medical attention as soon as possible.