If someone has hypothermia, call 911 immediately and begin warming them slowly, focusing on their core body, not their arms and legs. Hypothermia is a medical emergency at any stage, and the steps you take before help arrives can determine the outcome. Here’s exactly what to do and what to avoid.
How to Recognize Hypothermia
Hypothermia sets in when core body temperature drops below 95°F (35°C). In mild cases, you’ll notice shivering, clumsiness, slurred speech, and confusion. The person may seem unusually drowsy or make poor decisions. In infants, look for bright red, cold skin.
As it worsens (below about 90°F), shivering actually decreases or stops entirely, which can trick bystanders into thinking the person is improving. Other signs of moderate to severe hypothermia include a bluish tint to the skin, muscle stiffness, hallucinations, slowed breathing, and eventually loss of consciousness. The confusion that comes with hypothermia prevents the person from recognizing how much danger they’re in, which is why bystanders need to act.
Step-by-Step First Aid
Get Them Out of the Cold
Move the person indoors if possible. If you can’t, shield them from wind, especially around the head and neck, where heat loss is significant. Place a blanket, sleeping bag, tarp, or even a backpack beneath them to insulate against the cold ground. Ground contact drains body heat fast.
Remove Wet Clothing
Wet fabric pulls heat from the body far more quickly than dry air does. Gently remove wet clothing and replace it with dry layers or blankets. In severe cases where the person can’t be fully changed, at minimum wrap a dry layer against their skin and use a plastic bag or garbage bag as an outer barrier to stop evaporative cooling.
Warm the Core First
Focus warmth on the center of the body: the neck, chest, and groin. Use warm, dry compresses, an electric blanket, or a hot water bottle wrapped in a towel. Never place a heat source directly against bare skin. If you’re outdoors with nothing else available, body-to-body contact inside a sleeping bag works. Cover the person’s head to reduce heat loss.
If the person is alert enough to swallow safely, offer warm, sweet, nonalcoholic drinks. Sweet liquids provide a small energy boost that helps the body generate heat.
Handle Them Gently
This is one of the most important and least obvious rules. A hypothermic heart is electrically unstable. Between roughly 86°F and 93°F, the heart enters a vulnerable window where it’s prone to dangerous rhythm disturbances. Rough movements, jostling, or even vigorous rubbing of the limbs can trigger a potentially fatal heart rhythm called ventricular fibrillation. Move the person as smoothly and carefully as you can, keeping them horizontal when possible.
If They’re Unresponsive
Check for breathing, coughing, or any movement. If there are no signs of life, begin CPR and continue until emergency responders arrive. Hypothermic patients can survive much longer without a pulse than people at normal body temperature. There’s a well-known principle in emergency medicine: a hypothermic person should not be considered dead until they’ve been rewarmed. Prolonged CPR in these cases has saved lives that looked lost.
What Not to Do
Several common instincts can make hypothermia worse:
- Don’t rewarm too fast. A hot bath, heating lamp, or other intense heat source can cause a dangerous drop in blood pressure called rewarming shock. It can also trigger heart rhythm problems.
- Don’t warm the arms and legs. Heating the limbs pushes cold blood from the extremities back toward the heart and vital organs. This can actually cause core temperature to drop further, a phenomenon called “afterdrop.” In severe cases, afterdrop can push the heart below the threshold for cardiac arrest.
- Don’t give alcohol. Alcohol dilates blood vessels near the skin, which feels warming but actually accelerates heat loss from the core. It also impairs judgment further.
- Don’t massage the limbs. Rubbing the arms and legs has the same problem as warming them: it drives cold peripheral blood back to the heart and stresses a heart that’s already electrically fragile.
- Don’t give cigarettes. Nicotine constricts blood vessels and adds stress to an already compromised cardiovascular system.
Why Afterdrop Is Dangerous
Even after you start rewarming someone, their core temperature can continue to fall for a period. This happens because cold blood pooled in the arms and legs gradually circulates back to the core, mixing with warmer blood. In studies of hypothermic patients, this afterdrop lasted an average of about 20 minutes under normal shivering conditions but stretched to nearly 90 minutes when shivering was suppressed. The core temperature dropped an additional 1°F or more during that window.
This is why gradual, core-focused warming matters so much. If the heart’s temperature drops below roughly 82°F, spontaneous cardiac arrest becomes a real risk. Keeping the person still and warming only the torso minimizes afterdrop by limiting the flow of cold blood from the extremities back to the heart.
Mild vs. Severe: Why It Changes the Approach
Mild hypothermia (95°F to 90°F) is the only stage where the body can still effectively warm itself through shivering. Getting the person into a warm environment, removing wet clothes, wrapping them in blankets, and giving warm drinks may be enough. This is called passive rewarming: you’re removing the source of heat loss and letting the body do the rest.
Moderate hypothermia (90°F to 82°F) means the body’s own heating mechanisms are failing. Shivering weakens or stops. The person needs external heat sources applied to the core, plus emergency medical care. At this stage, confusion and drowsiness are severe, and the person likely can’t help themselves at all.
Severe hypothermia (below 82°F) is immediately life-threatening. The person may appear dead, with no visible breathing, no detectable pulse, and complete muscle rigidity. A coma at this stage can closely mimic death. Do not assume someone in severe hypothermia has died. Begin CPR if there are no signs of life, handle them as gently as possible, insulate them from further heat loss, and wait for emergency responders who can rewarm them with advanced techniques.
People at Highest Risk
Infants lose body heat much faster than adults because of their high surface-area-to-weight ratio and limited ability to shiver effectively. An infant with hypothermia may not shiver at all. Instead, look for unusually red, cold skin and low energy. Elderly adults are also highly vulnerable because the body’s temperature regulation weakens with age, and many medications further impair the ability to sense or respond to cold. Hypothermia in older adults can develop indoors, in homes that are simply poorly heated, at temperatures that wouldn’t affect a younger person.
Anyone who has been in cold water is at elevated risk because water conducts heat away from the body roughly 25 times faster than air at the same temperature. Even water that doesn’t feel dangerously cold, around 60°F, can cause hypothermia with prolonged exposure.