If someone near you has hypothermia, the most important things you can do are call emergency services, get them out of the cold, and warm their core gradually. How you rewarm them matters as much as whether you do it, because warming the wrong areas or warming too fast can trigger dangerous heart rhythms. Here’s what to do and what to avoid.
Recognizing Hypothermia
Hypothermia sets in when the body’s core temperature drops below 95°F (35°C). The tricky part is that people with hypothermia usually don’t realize it themselves. Confused thinking prevents self-awareness and can even lead to risk-taking behavior, so you may need to recognize the signs before they can ask for help.
Early signs include shivering, clumsiness, and slurred speech. As the body cools further, shivering may actually stop, breathing becomes slow and shallow, the pulse weakens, and drowsiness or confusion sets in. In the most serious cases, the person may lose consciousness entirely. In infants, look for bright red, cold skin. A useful memory trick: watch for the “umbles.” Stumbling, mumbling, fumbling, and grumbling all point to a body that is losing its ability to function in the cold.
Mild hypothermia falls between 95°F and 89.6°F. Moderate hypothermia ranges from 89.6°F down to 82.4°F. Severe hypothermia is anything below 82.4°F. You won’t know the exact number in the field, but the progression of symptoms tells you how serious things are. If the person has stopped shivering, is barely conscious, or is unresponsive, treat it as a medical emergency.
Step-by-Step First Aid
Call 911 (or your local emergency number) first. Then start these steps while you wait for help.
- Get them out of the cold. Move the person indoors if possible. If you can’t, shield them from the wind, especially around the head and neck. Insulate them from the ground with a blanket, sleeping bag, backpack, or even a layer of branches. Cold ground pulls heat from the body rapidly through direct contact.
- Remove wet clothing. Gently take off anything wet and replace it with dry coats, blankets, or sleeping bags. Be gentle with your movements. Rough handling of a severely hypothermic person can trigger a dangerous heart rhythm.
- Warm the core first. Apply warm, dry compresses to the neck, chest, and groin. An electric blanket works well if you have one. If you’re using a hot water bottle or chemical heat pack, wrap it in a towel before placing it on the skin. Focus all warming on the center of the body.
- Offer warm, sweet drinks. If the person is conscious and alert enough to swallow safely, give them warm, sweetened, nonalcoholic fluids. Hot cocoa, warm water with sugar, or warm broth all work. The sugar provides quick fuel for the body’s heat production.
- Cover their head. A significant amount of heat escapes through an uncovered head. A hat, hood, or even a spare shirt draped over the head helps.
- Use a vapor barrier. If you’re outdoors, wrapping the person in a tarp, emergency blanket, or even a plastic bag (over the dry layers, not against skin) traps heat and blocks wind and moisture.
What Not to Do
Some well-meaning actions can make hypothermia worse or become outright dangerous.
Do not warm the arms and legs directly. Heating or massaging the limbs pushes cold blood from the extremities back toward the heart and lungs, which can cause a sudden further drop in core temperature and stress the cardiovascular system. This phenomenon is called “afterdrop,” where the core temperature actually continues to fall during the early stages of rewarming because cold blood from the outer tissues reaches the organs before external heat does. Focusing warmth on the trunk helps prevent this.
Do not use a hot bath, heating lamp, or any other method that rewarms the person quickly. Rapid external rewarming triggers the same dangerous return of cold blood to the core. Do not give alcohol. It feels warming but actually widens blood vessels near the skin, accelerating heat loss. Do not rub or vigorously massage the person’s body. And do not assume the person is fine just because they say they feel okay. Confused thinking is one of the hallmarks of hypothermia.
If the Person Is Unresponsive
Check for breathing, coughing, or any movement. If you see no signs of life, begin CPR immediately and continue at the normal rate. Hypothermia slows the body’s processes so dramatically that a person can appear dead, with fixed, dilated pupils and a body that feels rigid, yet still be recoverable. Medical guidelines are clear: do not stop resuscitation based on how cold the person feels or how unresponsive they appear. There is a saying in emergency medicine that a hypothermic patient is “not dead until they’re warm and dead.”
If an automated external defibrillator (AED) is available, use it. Follow its prompts. If it advises a shock, deliver it and then continue CPR. If it advises no shock, check for a pulse at the neck for at least a full minute. If you find no pulse, no breathing, and no other signs of life, continue CPR until emergency responders arrive.
How Hospitals Rewarm Patients
For mild cases, the body can often rewarm itself once it’s sheltered, dry, and insulated. This passive approach relies on the person’s own shivering to generate heat. For moderate hypothermia, hospitals add external warming with heated blankets or forced warm air systems, while monitoring closely for afterdrop.
Severe hypothermia requires warming from the inside out. The simplest version involves warmed IV fluids and heated, humidified oxygen delivered through a mask. In more critical cases, doctors may flush warm saline into the chest or abdominal cavity through thin tubes. The most aggressive method draws the patient’s blood out of the body, warms it, and pumps it back in using a machine similar to a dialysis unit. This approach can rewarm someone rapidly while continuing to deliver oxygen to the tissues, even if the heart isn’t beating on its own. The key advantage of all core-rewarming methods is that they heat the organs directly, avoiding the afterdrop problem that makes external warming risky in severe cases.
Mild Hypothermia You Can Manage at Home
Not every case of hypothermia requires an ambulance. If someone is shivering, alert, and able to move and talk normally, they likely have mild hypothermia and may recover with basic care: getting indoors, changing into dry clothes, wrapping up in blankets, drinking warm sweet fluids, and staying warm for several hours. Their own shivering is an effective heat generator at this stage.
The line between “handle at home” and “call for help” is whether the person can still shiver, think clearly, and coordinate their movements. Once shivering stops, speech becomes slurred, or confusion sets in, they need emergency medical care. When in doubt, call. Hypothermia worsens quickly, and a person who seems mildly cold can deteriorate in minutes if the underlying cause isn’t addressed.