Treating a hypothermia victim starts with one principle: warm them slowly and handle them gently. A body temperature below 35°C (95°F) qualifies as hypothermia, and the severity of the situation determines how aggressively you need to act. In mild cases, simple insulation and shelter can be enough. In severe cases, the wrong move, even something as well-intentioned as rubbing someone’s arms to warm them up, can trigger a fatal heart rhythm.
Recognizing the Three Stages
Hypothermia falls into three categories based on core body temperature, and each stage looks noticeably different.
Mild (32–35°C / 90–95°F): The person is shivering, possibly confused, and has poor coordination. They can still talk and follow instructions. This is the most common form and the most treatable in the field.
Moderate (28–32°C / 82–90°F): Shivering may slow down or stop entirely, which is a bad sign, not a good one. The person becomes drowsy, slurs words, and may not realize how much trouble they’re in. Decision-making deteriorates sharply.
Severe (below 28°C / 82°F): The person may be unconscious, breathing very slowly, or appear dead. The heart becomes electrically unstable at these temperatures, meaning even jostling the person can cause it to stop beating effectively. Severe hypothermia with hemodynamic instability is frequently fatal without advanced hospital-based rewarming.
Immediate Steps Anyone Can Take
The first priority is stopping further heat loss. Get the person out of the cold environment. If you can’t move them indoors, shield them from wind, especially around the head and neck, where heat escapes fastest. Insulate them from the ground, because cold ground pulls heat from the body far more efficiently than cold air. A blanket, sleeping pad, backpack, or even a pile of branches underneath them makes a real difference.
Remove wet clothing and replace it with dry layers or blankets. Wet fabric conducts heat away from the body roughly 25 times faster than dry air, so leaving wet clothes on essentially keeps the cooling process going even after you’ve brought someone inside. Be gentle during this process. Avoid pulling limbs around or forcing the person to stand up and walk.
Why Gentle Handling Matters
A cold heart is an irritable heart. The American Heart Association specifically warns that physical manipulation of a hypothermic person can precipitate ventricular fibrillation, a chaotic heart rhythm that prevents the heart from pumping blood. This risk increases as core temperature drops. In moderate and severe cases, keep the person as still as possible. Carry them horizontally if you need to move them. Avoid rubbing or massaging their arms and legs, no matter how intuitive that feels.
The Hypothermia Wrap
If you’re in a remote setting waiting for rescue, wrapping the person properly can significantly slow heat loss. The most effective field method uses a vapor barrier layer (a plastic sheet, garbage bags, or even a tarp) wrapped around the body from neck to toes, sealed as well as possible, and then covered with insulating layers like blankets or sleeping bags. Research published in the European Journal of Anaesthesiology found that this combination of a plastic layer plus blankets maintained skin temperature significantly better than blankets or bubble wrap alone. It’s cheap, lightweight, and easy to improvise.
The logic is straightforward: the plastic traps moisture and prevents evaporative heat loss, while the blankets slow conductive and convective cooling. Cover the head too, since an uncovered head radiates a substantial amount of body heat.
Rewarming Methods by Severity
Mild Hypothermia
Passive rewarming works well here. This means relying on the person’s own body to generate heat once you’ve stopped the cooling process. Remove them from the cold, replace wet clothing, insulate them thoroughly, and let their metabolism do the work. If they’re alert enough to swallow safely and protect their airway, warm (not hot) drinks can help. Avoid alcohol, which dilates blood vessels and actually accelerates heat loss.
Moderate Hypothermia
Passive rewarming alone may not be enough because the body’s shivering mechanism is failing. Active external rewarming adds heat from the outside: warm water bottles, chemical heat packs, or warm blankets placed against the torso, armpits, and groin. Focus heat on the core, not the extremities. Warming the arms and legs first pushes cold blood from the limbs back toward the heart, which can cause a dangerous further drop in core temperature.
Severe Hypothermia
This requires hospital care. Standard medical rewarming includes warmed intravenous fluids (heated to about 44°C), warmed humidified oxygen, and in some cases, lavage, where warm fluid is circulated through body cavities like the bladder or abdomen. For patients in cardiac arrest or with profound instability, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass can rewarm the blood directly outside the body. These machines simultaneously warm the patient, support circulation, and maintain oxygen delivery to tissues. Remarkably, neurological outcomes after ECMO rewarming are often very good, even after prolonged CPR.
Understanding Afterdrop
One of the most counterintuitive dangers of hypothermia treatment is afterdrop: the core body temperature continues to fall even after rewarming has begun. This happens because heat moves through tissue gradually. When someone has been cold for a while, their outer tissues are much colder than their core. When you start warming the surface, the established temperature gradient doesn’t reverse instantly. Heat continues flowing outward from the warmer core toward the still-cold outer layers, pulling the core temperature down further before it starts climbing back up.
Afterdrop is one reason rewarming should be slow and focused on the trunk. It’s also why a person who seemed stable can suddenly deteriorate during the early phase of treatment. Keep monitoring them even after you’ve started warming them up.
What Not to Do
- Don’t rub or massage the limbs. This can push cold, stagnant blood from the extremities into the core and trigger dangerous heart rhythms.
- Don’t give fluids to someone who can’t swallow safely. If the person is drowsy, confused, or unable to protect their airway, oral fluids create an aspiration risk.
- Don’t apply direct heat to the skin. Hot water bottles or heating pads placed directly against skin can cause burns, because hypothermic tissue has reduced blood flow and reduced sensation. Use a cloth barrier.
- Don’t warm the extremities first. Focus heat on the chest, armpits, neck, and groin to protect the heart from cold blood returning from the limbs.
- Don’t assume someone is dead. Severe hypothermia can mimic death. Breathing and pulse may be undetectable. The longstanding principle in emergency medicine is that a hypothermic person is not dead until they are warm and dead, meaning resuscitation efforts should continue until the person has been rewarmed.
Keeping Yourself Safe While Helping
If someone fell through ice or was caught in a river, don’t rush in after them. Reach or throw something to them if possible. If you’re in a wilderness setting, get yourself sheltered and insulated too, because two hypothermic people is a worse situation than one. Call for emergency medical help as early as possible. Even mild hypothermia can progress quickly in wet or windy conditions, and moderate to severe cases need professional intervention to rewarm safely.