[3] In severe hypothermia, there may be hallucinations and paradoxical undressing, in which a person removes their clothing, as well as an increased risk of the heart stopping.

[2] If there is no improvement at this point or the blood potassium level is greater than 12 millimoles per litre at any time, resuscitation may be discontinued.

[5] One of the lowest documented body temperatures from which someone with accidental hypothermia has survived is 12.7 °C (54.9 °F) in a 2-year-old boy from Poland named Adam.

Infants with hypothermia may feel cold when touched, with bright red skin and an unusual lack of energy.

[19] As hypothermia progresses, symptoms include: mental status changes such as amnesia, confusion, slurred speech, decreased reflexes, and loss of fine motor skills.

[17] There is often cold, inflamed skin, hallucinations, lack of reflexes, fixed dilated pupils, low blood pressure, pulmonary edema, and shivering is often absent.

[21][22] Rescuers who are trained in mountain survival techniques are taught to expect this; however, people who die from hypothermia in urban environments who are found in an undressed state are sometimes incorrectly assumed to have been subjected to sexual assault.

[26] Researchers in Germany claim this is "obviously an autonomous process of the brain stem, which is triggered in the final state of hypothermia and produces a primitive and burrowing-like behavior of protection, as seen in hibernating mammals".

[30] In urban areas, hypothermia frequently occurs with chronic cold exposure, such as in cases of homelessness, as well as with immersion accidents involving drugs, alcohol or mental illness.

[32] In more rural environments, the incidence of hypothermia is higher among people with significant comorbidities and less ability to move independently.

[31] With rising interest in wilderness exploration, and outdoor and water sports, the incidence of hypothermia secondary to accidental exposure may become more frequent in the general population.

[31] Alcohol consumption increases the risk of hypothermia in two ways: vasodilation and temperature controlling systems in the brain.

[35] The reduction in finger dexterity due to pain or numbness decreases general safety and work capacity, which consequently increases the risk of other injuries.

For example, plunged into freezing seas, around 20% of victims die within two minutes from cold shock (uncontrolled rapid breathing, and gasping, causing water inhalation, massive increase in blood pressure and cardiac strain leading to cardiac arrest, and panic); another 50% die within 15–30 minutes from cold incapacitation: inability to use or control limbs and hands for swimming or gripping, as the body "protectively" shuts down the peripheral muscles of the limbs to protect its core.

[37] Heat is primarily generated in muscle tissue, including the heart, and in the liver, while it is lost through the skin (90%) and lungs (10%).

Some synthetic fabrics, such as polypropylene and polyester, are used in clothing designed to wick perspiration away from the body, such as liner socks and moisture-wicking undergarments.

Several studies have shown that for uncovered infants, lined hats significantly reduce heat loss and thermal stress.

[54][55][56] Children have a larger surface area per unit mass, and other things being equal should have one more layer of clothing than adults in similar conditions, and the time they spend in cold environments should be limited.

[16] In severe cases resuscitation begins with simultaneous removal from the cold environment and management of the airway, breathing, and circulation.

[63] The UK National Health Service advises against putting a person in a hot bath, massaging their arms and legs, using a heating pad, or giving them alcohol.

[65] Passive external rewarming involves the use of a person's own ability to generate heat by providing properly insulated dry clothing and moving to a warm environment.

[66] When severe hypothermia has led to cardiac arrest, effective extracorporeal warming results in survival with normal mental function about 50% of the time.

[2] These concerns were partly believed to be due to afterdrop, a situation detected during laboratory experiments where there is a continued decrease in core temperature after rewarming has been started.

[70] As most hypothermic people are moderately dehydrated due to cold-induced diuresis, warmed intravenous fluids to a temperature of 38–45 °C (100–113 °F) are often recommended.

[50] If a person was buried in an avalanche for more than 35 minutes and is found with a mouth packed full of snow without a pulse, stopping early may also be reasonable.

[32] Hypothermia has played a major role in the success or failure of many military campaigns, from Hannibal's loss of nearly half his men in the Second Punic War (218 B.C.)

Men wandered around confused by hypothermia, some lost consciousness and died, others shivered, later developed torpor, and tended to sleep.

[79] Nazi human experimentation during World War II amounting to medical torture included hypothermia experiments, which killed many victims.

[84] In 2024, at least six babies in Gaza died of hypothermia under the harsh rain and cold, which they had to endure in flimsy camps due to the bombing of their homes and forced displacement inflicted upon them by the IDF.

The time limit for this technique, as also for accidental arrest in ice water (which internal temperatures may drop to as low as 15 °C), is about one hour.