Treating hypothermia starts with getting the person out of the cold, insulating them, and focusing warmth on the core of the body. The specific steps depend on how far their body temperature has dropped: mild hypothermia (90°F to 95°F) can often be reversed in the field, while moderate and severe cases (below 90°F) require careful handling and medical intervention to avoid dangerous heart rhythms.
Recognizing the Severity
Outside a hospital, hypothermia is diagnosed by how the person looks and acts, not by a thermometer reading. Core temperature is difficult to measure accurately in the field, so physical signs guide treatment decisions.
In early or mild hypothermia, the person will be shivering, possibly confused, fatigued, and losing coordination. Shivering is actually a good sign: it means the body is still actively generating heat. As hypothermia worsens into moderate and severe stages, shivering stops entirely. The skin turns blue, the pulse slows, pupils dilate, and the person may lose consciousness. The absence of shivering in someone who is clearly cold is a red flag that the situation has become serious.
Immediate First Aid Steps
Whether you’re on a trail, at a campsite, or helping someone indoors, these steps apply to all levels of hypothermia:
- Move the person out of the cold. If you can’t get indoors, shield them from wind, especially around the head and neck.
- Insulate from the ground. Lay a blanket, sleeping pad, or extra clothing underneath them. Cold ground pulls heat from the body fast.
- Remove wet clothing carefully. Replace it with dry layers, coats, or blankets. In cold outdoor conditions, the Wilderness Medical Society recommends waiting to remove wet clothes until the person is in a warm or sheltered environment so they aren’t exposed further during the change.
- Apply warmth to the core. Place warm compresses, a wrapped hot water bottle, or chemical heat packs against the neck, chest, armpits, and back. Never apply heat directly to bare skin, as burns can occur if tissue temperature exceeds about 109°F.
- Offer warm, sweet drinks if the person is mildly hypothermic, alert, and able to swallow. Skip this entirely for moderate or severe cases.
- Begin CPR if the person shows no signs of life: no breathing, no coughing, no movement. Check for a pulse at the neck for a full 60 seconds, because a hypothermic heart may beat very slowly and be hard to detect through cold skin.
What Not to Do
Some instinctive responses to hypothermia can make things worse. Do not rewarm the person rapidly with a hot bath or heating lamp. Do not rub or massage their arms and legs, and do not apply heat to the limbs. Warming the extremities pushes cold blood from the arms and legs back toward the heart, which can cause the core temperature to drop even further. This phenomenon, called afterdrop, increases the risk of a dangerous heart rhythm.
Do not give alcohol. It feels warming but actually accelerates heat loss by dilating blood vessels near the skin. Tobacco products should also be avoided because they constrict blood vessels and impair the circulation needed for rewarming.
Why Gentle Handling Matters
In moderate or severe hypothermia, the heart becomes extremely sensitive to physical disturbance. Rough handling, jostling during clothing removal, or even moving the person from horizontal to upright can trigger ventricular fibrillation, a type of cardiac arrest. Keep the person lying flat, move them as smoothly as possible, and avoid unnecessary repositioning. The Wilderness Medical Society specifically recommends keeping moderately hypothermic patients horizontal to prevent afterdrop from redistributing cold blood to the heart.
Treating Mild Hypothermia in the Field
A person with mild hypothermia (core temperature roughly 90°F to 95°F) is still shivering and at least somewhat alert. Shivering itself is a powerful rewarming mechanism. Research shows that when shivering is suppressed, the afterdrop in core temperature more than triples in magnitude and takes over four times longer to resolve. So protecting the body’s ability to shiver, by insulating the person, blocking wind, and providing calories, is one of the most effective things you can do.
Apply heat packs or warm compresses to the upper trunk: armpits, chest, and back. Give warm, calorie-rich food or drinks if the person can swallow safely. Have them rest for at least 30 minutes. If they’re improving after that time, gentle movement or light exercise can help generate body heat. If there’s no improvement in 30 minutes, evacuate to medical care.
Treating Moderate and Severe Hypothermia
Once hypothermia progresses past the mild stage, field options become limited and the priority shifts to preventing further heat loss while getting the person to a hospital. Do not give food or drink. Keep them horizontal and insulated, with heat applied only to the upper trunk. If you have access to warm intravenous fluids, they can help replace volume, but this is typically only available to trained rescuers.
Severe hypothermia, where core temperature drops below about 82°F, is a medical emergency that requires hospital-based rewarming. In-hospital techniques include warmed humidified oxygen, warm intravenous saline (heated to about 109°F), flushing the chest or abdominal cavity with warm fluid, and in the most critical cases, routing the blood through an external warming machine. These methods target the core directly and can rewarm a patient much faster than external heat alone.
The target rewarming rate in a clinical setting is deliberately slow: European resuscitation guidelines recommend raising core temperature by only about 0.5°F to 1°F per hour. Rewarming too quickly can cause dangerous shifts in blood chemistry, blood pressure, and heart rhythm.
CPR and Cardiac Arrest in Hypothermia
Hypothermia creates a unique situation when it comes to cardiac arrest. A severely cold body has a dramatically reduced need for oxygen, which means the brain and organs can sometimes survive much longer without a pulse than they would at normal temperature. This is why the saying “nobody is dead until they’re warm and dead” exists in emergency medicine.
If you need to perform CPR on a hypothermic person, follow standard chest compressions and rescue breaths. If rescue conditions force you to interrupt CPR (during transport over rough terrain, for example), aim for five minutes of compressions with no more than five-minute breaks between rounds. Defibrillation should be attempted at maximum power, but if the core temperature is below about 86°F and the first shock doesn’t work, additional shocks are generally delayed until the person has been warmed past that threshold. Ventilation should be delivered at about half the normal rate, because a cold body produces far less carbon dioxide and over-ventilating can cause harm.