A decreased body temperature can occur in patients with hypothermia and frostbite. Heat loss with extended cold exposure overpowers the body's ability to create heat, resulting in hypothermia. Core temperature readings help classify hypothermia. Mild hypothermia is temperatures between 32 °C (89.6 °F) and 35°C (95 °F) and is caused by impaired thermoregulation. Moderate hypothermia is temperatures between 28 C (82.4 °F) and 32 °C (89.6 °F) caused by sustained extreme cold exposure, and severe hypothermia is temperatures below 28°C (82.4 °F) caused by prolonged exposure to extreme cold.

Hypothermia can be accidental, such as drowning in cold water, or intentionally caused during surgical or emergency treatments to reduce metabolism and the body's requirement for oxygen. Although hypothermia is most frequent in individuals exposed to low temperatures, it can also occur as a result of toxin exposure, metabolic imbalances, infections, and central nervous and endocrine system dysfunction. Accidental hypothermia is more common in older adults and goes unnoticed.

The symptoms of hypothermia include shivering, memory loss, depression, and impaired judgment. It can also cause a slowed heart rate, shallow breathing, weak pulse, and low blood pressure. The skin begins to get cyanotic. If hypothermia worsens, patients endure cardiac dysrhythmias and loss of consciousness and become insensitive to painful stimuli. In severe situations, a person exhibits clinical indications akin to death.

Frostbite develops when the body is exposed to temperatures below normal. Inside the cells, ice crystals accumulate, causing irreversible circulation and tissue damage. Earlobes, the tip of the nose, toes, and fingers, are particularly vulnerable to frostbite. The affected region turns white, waxy, and stiff to the touch, along with numbness. Interventions include slow warming, analgesia, and injured tissue protection.

Critical nursing interventions to prevent a further drop in body temperature include removing damp clothing, replacing it with dry garments, and ensuring patients are snugly covered with blankets. In an emergency outside of a hospital, have the patient rest under blankets adjacent to a warm person. A conscious patient benefits from consuming hot liquids like soup and avoiding alcohol and caffeinated beverages. It is also beneficial to cover the patient's head, bring the patient near the fire or in a warm room, or place heating pads close to regions of the body that lose heat the fastest, for example, the head and neck.