Hypothermia Recognition and Rewarming

Part of First Aid

Hypothermia kills more people in survival situations than almost any other condition. Recognizing it early and knowing how to reverse it will save lives in your group.

What Is Hypothermia

Hypothermia occurs when the body’s core temperature drops below 35°C (95°F). The body loses heat faster than it can produce it, and organ systems begin to shut down. In a post-collapse world without heated buildings or emergency services, exposure to cold rain, wind, or immersion in water can trigger hypothermia in as little as 20-30 minutes.

The critical thing to understand: hypothermia victims often don’t recognize their own condition. The brain slows down along with the body. You must watch for it in others.

Recognizing the Stages

Hypothermia progresses through distinct stages. The earlier you catch it, the easier it is to reverse.

Stage	Core Temp	Signs	Urgency
Mild	32-35°C (90-95°F)	Shivering, cold hands/feet, fumbling, slurred speech, poor decisions	Act now — fully reversible in the field
Moderate	28-32°C (82-90°F)	Shivering stops, confusion, drowsiness, slow pulse, stumbling	Serious — requires careful rewarming
Severe	Below 28°C (82°F)	Unconscious, very slow/absent pulse, rigid muscles, appears dead	Life-threatening — gentle handling critical

The Shivering Threshold

Shivering is the body’s last-ditch effort to generate heat. When someone who was shivering suddenly stops but is still cold, they have gotten worse, not better. This is one of the most commonly misread signs.

Paradoxical Undressing

In moderate to severe hypothermia, victims sometimes strip off their clothing. The blood vessels near the skin suddenly dilate, creating a false sensation of burning heat. If you find someone undressed in cold conditions, suspect hypothermia immediately.

The “Umbles” Rule

Watch for the umbles — the easiest field diagnostic:

• Stumbles — loss of coordination, tripping, can’t walk straight
• Mumbles — slurred or slow speech, can’t finish sentences
• Fumbles — drops things, can’t use fingers, struggles with zippers
• Grumbles — irritable, combative, refuses help, irrational anger

Two or more umbles in cold conditions means hypothermia until proven otherwise.

Field Assessment Without a Thermometer

You won’t have a medical thermometer in most survival situations. Use these checks:

1. Touch the torso — Place your warm hand on their abdomen or chest (under clothing). If the trunk feels cold to your touch, they are hypothermic.
2. Check mental state — Ask them to count backward from 100 by 7s. Hypothermic people cannot do simple math.
3. Test coordination — Have them touch their nose with their finger. Failure indicates at least moderate hypothermia.
4. Check pulse — Feel the carotid artery (side of neck) for 60 full seconds. A very slow or irregular pulse indicates moderate-to-severe hypothermia.

Critical Rule

In severe hypothermia, the heart is extremely irritable. Rough handling — dropping, jostling, rapid movement — can trigger fatal cardiac arrest. Move severe hypothermia victims slowly and gently, keeping them horizontal.

Immediate Field Response

Step 1: Stop the Heat Loss

Before you can rewarm someone, you must stop the ongoing heat drain:

• Get them out of wind and wet. Into a shelter, behind a windbreak, into a vehicle — anything.
• Remove wet clothing. Cut it off if necessary. Wet fabric pulls heat from the body 25 times faster than dry air.
• Insulate from the ground. The ground steals heat rapidly through conduction. Use pine boughs, a foam pad, dry leaves, a backpack — anything between them and the earth.
• Cover the head and neck. Up to 40% of heat loss occurs from the head in cold conditions.

Step 2: Create a Heat Cocoon

Wrap the victim in every layer of dry insulation available:

• Dry blankets, sleeping bags, spare clothing
• Emergency space blankets (reflective side facing the person)
• If nothing else, your own dry clothing

The goal is to trap whatever body heat remains and add external warmth. See Rewarming Steps for detailed active rewarming techniques.

Step 3: Add External Heat

For mild hypothermia:

• Warm drinks — Not hot, just comfortably warm. Sweet drinks (sugar water, honey water) provide calories for the body to burn. Never give alcohol — it dilates blood vessels and accelerates core heat loss.
• Skin-to-skin contact — The single most effective field rewarming method. See Rewarming Steps.
• Warm water bottles — Fill containers with warm (not hot) water and place them at the neck, armpits, and groin where major blood vessels run close to the surface.

For moderate-to-severe hypothermia:

• Do not give fluids to someone who is confused or unconscious — aspiration risk.
• Rewarm slowly — Rapid rewarming of a severely hypothermic person can cause “afterdrop,” where cold blood from the extremities rushes to the core and drops core temperature further. This can stop the heart.
• Focus heat on the core — Trunk, armpits, groin. Do not rub or heat the arms and legs.

Common Mistakes That Kill

1. Putting the victim near a roaring fire. Rapid surface heating causes blood vessel dilation, drops blood pressure, and triggers afterdrop. Warm them gradually.
2. Rubbing the extremities. This pushes cold blood toward the heart. Never massage hypothermic limbs.
3. Giving alcohol. It feels warming but causes vasodilation and accelerates heat loss.
4. Letting them walk or exercise. Movement circulates cold peripheral blood to the core. Keep them still and horizontal.
5. Assuming someone is dead. Severe hypothermia mimics death — very slow pulse, no visible breathing, fixed pupils. The rule: “Nobody is dead until they are warm and dead.” Attempt rewarming before giving up.

Prevention

The best treatment is prevention:

• Stay dry. Change wet socks and clothing immediately.
• Eat regularly. Calories are fuel for heat production. High-fat foods provide the most sustained warmth.
• Stay hydrated. Dehydration accelerates heat loss.
• Watch each other. Assign buddy checks in cold weather.
• Recognize early signs and act immediately. Mild hypothermia caught early takes 30 minutes to reverse. Severe hypothermia can take hours and may still fail.

Key Takeaways

• Hypothermia kills by stealth — victims don’t recognize their own decline. Watch others for the “umbles.”
• When shivering stops but the person is still cold, they are getting worse, not better.
• Stop heat loss first (remove wet clothes, insulate from ground, block wind), then add warmth to the core.
• Handle severe cases gently and horizontally — rough handling can trigger cardiac arrest.
• Never assume a cold, unresponsive person is dead. Rewarm them first.