Medical Intervention

If further care is required, different techniques may be used to rewarm the body based on the severity of the hypothermia:

Passive External Rewarming

Passive external rewarming (PER) is typically used to treat mild hypothermia. It simply involves placing the individual in an appropriately warm environment, covered in insulation, and gradually raising the core body temperature a few degrees every hour.

Active Core Rewarming

PER cannot be used if a person’s temperature drops below 86 degrees. It is at this stage that spontaneous shivering will stop and the body will no longer be able to increase the temperature on its own. By that point, the heart will be unstable and the use of external heat will only increase the risk of arrhythmia.  

There are several ways this can be done:

  • Feeding warm, humidified air into the lung with an oxygen mask or breathing tube
  • Administering warm fluids intravenously (into a vein)
  • Irrigating the abdomen (peritoneal cavity) or the space around the lungs (pleura) with warm salt water every 20 to 30 minutes
  • Administering warm fluids into the bladder with a Foley catheter
  • Rewarming the blood with a hemodialysis machine or a heart bypass machine
  • Using diathermy, a technique in which low-frequency microwave radiation can deliver heat to deeper tissues

Treatment Follow-Up

Generally speaking, someone with hypothermia is released home after treatment is complete if his or her body temperature was above 89.9 degrees at the time of diagnosis.

If body temperature was ever below 89.9 degrees, hospitalization and monitoring for no less than 24 hours, until vital functions are stabilized, is required.



Once you have the individual sheltered from the cold and have removed any wet clothing, you will need to take the appropriate action to rewarm the body until help arrives.

To do so safely:

  • Be gentle. Avoid rubbing the person aggressively. Someone who has experienced severe exposure will often have an irregular heart rate. Jarring, moving, or massaging the person vigorously may trigger cardiac arrest.
  • Give warming drinks. Do so only if the person is alert and able to swallow. Provide warm, sweet, non-caffeinated beverages. Avoid alcohol of any sort as this will only cool the body even further.
  • Use warm, dry compresses, ideally a first aid instant warming compress (a plastic bag that heats up when squeezed), a dryer-warmed towel, or electric heating pad set on low.
  • Avoid intense heat of any sort. This includes a blow heater, radiant heater, or a hot water bath. Overheating the skin can lead to tissue damage or, even worse, trigger potentially deadly arrhythmia (irregular heartbeats).
  • Avoid warming the arms or legs as this forces the cold back to the heart, lungs, and brain, further lowering the body temperature and increasing the risk of organ failure. Instead, focus the attention primarily on the chest, groin, and neck where the major arteries are located.

Stopping Heat Loss

Hypothermia occurs when the core body temperature—the temperature of the organs and blood in the center of the body, not the skin—drops below 95 degrees.

This may happen in a number of situations, such as when someone is out in cold weather for too long or falls into icy water. People who are wet will lose body heat faster than those who are dry. Similarly, windy conditions can steal heat away from the body faster than in still conditions. People with severe injury also are at risk for hypothermia.

To do this:

  1. Move the person out of the cold, ideally to a dry, warm location. If you can’t get indoors, shield the person from the cold and wind, keeping him or her in a horizontal position so that the blood can circulate more freely.
  2. Remove wet clothing. Cut away the clothing if you need to and immediately cover the person with dry blankets or coats. Be sure to cover the person’s head, leaving the face exposed.
  3. Insulate the person from the cold ground if you are unable to get indoors. Use blankets, sleeping bags, or whatever clothing you may have on hand.
  4. Call 911. If the person’s breathing has stopped or is abnormally low, or the pulse is very weak, begin CPR if you have been trained to do so.

Regardless of the cause or your certainty of a case of hypothermia, if you are with someone who is experiencing signs and symptoms—low heart rate and shallow respiration are particularly concerning—you need to act quickly by first stopping the loss of body heat.


How Hypothermia Is Treated

Hypothermia is a medical emergency in which your body loses heat faster than it can produce it, causing a dangerous drop in the core body temperature. Without rapid and decisive treatment, the heart, lungs, and other organs can begin to shut down, leading to organ failure and death.

Medical treatment may involve passive rewarming, warming intravenous infusions, blood rewarming, and the irrigation of the lungs and abdomen with warm salt water.

The primary aim is to remove the victim from the cold and to rewarm his or her body safely until emergency services arrive.


Differential Diagnoses

Hypothermia can mimic other medical conditions and those are best ruled out by a healthcare provider. Even shivering is not necessarily a sign of hypothermia. Fever and chills can cause shivering, as can withdrawal from opiate use.

If the patient is shivering and having difficulty with fine motor skills but doesn’t have a body temperature below 95 degrees, it isn’t hypothermia.

Likewise, if a patient is hypothermic with a body temp below 95 degrees and is unconscious, the diagnosis is hypothermia, but the patient could very easily have other conditions as well.

The gold standard for hypothermia diagnosis is to use the core body temperature.


Obtaining Accurate Results

To truly diagnose hypothermia, an accurate body temperature reading is necessary.

There are many ways to take a temperature. Unlike the pre-digital age, when the only thermometers were glass tubes containing toxic mercury, modern thermometers can take temperatures inside and outside the body. Some can take a temperature by barely touching the patient.

  • Forehead thermometers provide a simple, accurate option. Their biggest drawback is that they are expensive.
  • Rectal thermometers are a bit faster and considered the most accurate at-home option for a thermometer. They are much more economical than a forehead thermometer.
  • Oral thermometers use essentially the same thermometer as a rectal temperature, but must be used properly to get an accurate reading. The accuracy of an oral temperature is not as good as that of a rectal temp. Using an oral thermometer and taking the temperature under the arm (axillary) is extremely inaccurate and not recommended.
  • Tympanic thermometers (in the ear) that can be obtained over the counter are fast but notoriously inaccurate. These do not make contact with the tympanic membrane like the professional versions do and require proper use to work correctly.


The body temperature will dictate the severity of the hypothermia.1

Mild Hypothermia

This is the least dangerous stage of hypothermia and is defined as a core body temperature below 95 degrees. It comes with shivering, trouble concentrating, fumbling fingers, and discomfort.

Moderate Hypothermia

This stage is not as well defined as mild hypothermia, but is usually diagnosed as a core body temperature below 90 degrees and includes dilated pupils, confusion, fatigue, and eventually a loss of consciousness.

Severe Hypothermia

This stage entails a core body temperature below 83 degrees and the patient is likely to be unconscious and completely unresponsive.


Why Diagnosis Is Important

Most people don’t really think of mild hypothermia as being a medical condition that needs a diagnosis. Typically, we think of it as simply feeling too cold, in which case we take steps to avoid the discomfort associated with it—we go inside and turn up the heat, or put on a sweater and get a hot cup of cocoa.

Being able to clearly recognize hypothermia, however, means that the body’s mechanisms to stay warm are not sufficient. A diagnosis gives the patient an opportunity to treat the hypothermia before it gets worse.

It becomes more important to diagnose hypothermia when there is pressure to remain in the cold environment—someone who works outside or is injured, for example, can’t escape the cold. 


How Hypothermia Is Diagnosed

Hypothermia is both a medical condition as well as the description of an abnormal vital sign (low body temperature). In theory, diagnosing hypothermia should be fairly straightforward: Take a temperature and if it is below a defined threshold, the patient has hypothermia.

In reality, not all thermometers are the same and taking temperatures in different parts of the body will produce different values.


When to See a Doctor

The mildest hypothermia can be treated without any help from a healthcare provider. Simply moving the patient to a warm, dry environment will usually do the trick.

While waiting for an ambulance, if possible, move the patient to a dry, warm environment. Remove any wet clothes. A dry patient with a thin blanket is better than a patient covered in multiple layers of wet clothing.

Moderate to severe hypothermia requires the intervention of a healthcare provider. Always call 911 for a patient who is confused or unconscious, even if the cause is unknown.