When temperatures drop, the body is exposed to cold-related injuries, with frostbite and hypothermia representing two distinct medical emergencies. Although both conditions result from cold exposure, they affect the body in fundamentally different ways and require separate treatment approaches. Understanding the specific physiological impact of each is important, as confusing the two can delay proper care. This article clarifies the core difference between these conditions, details their varied symptoms, and outlines the appropriate first-aid response for each.
The Fundamental Difference: Localized vs. Systemic Impact
Frostbite is a localized injury, confined to a specific area of the body, most commonly the extremities like fingers, toes, nose, and ears. The physiological mechanism involves the freezing of tissues, which occurs when the skin temperature drops below the freezing point of water, often around 32°F (0°C). Initial damage occurs as ice crystals form in the fluid surrounding the cells, known as the interstitial space.
This extracellular freezing draws water out of the cells to maintain osmotic balance, leading to cellular dehydration and increased electrolyte concentration. If exposure continues, ice crystals may form inside the cells, causing mechanical damage and rupture. This process also initiates vascular damage, where blood vessels constrict and micro-clots form, leading to ischemia (lack of blood flow), which continues to cause tissue damage even after warming.
Hypothermia, conversely, is a systemic condition, affecting the entire body and its major organ systems. It is defined by a drop in the body’s core temperature below 95°F (35°C). This condition develops when the body loses heat faster than it can produce it, causing a failure of the body’s temperature regulation system.
The drop in core temperature slows metabolic processes in all organs, including the brain and heart, which can eventually lead to cardiac arrest. Unlike the direct tissue freezing of frostbite, hypothermia is a progressive decline in internal warmth that compromises the central nervous system, circulation, and respiratory function. Hypothermia is a widespread failure of the body’s internal machinery, whereas frostbite is a localized skin and tissue injury.
Identifying the Stages and Symptoms
Frostbite progresses through distinct stages, beginning with frostnip, the mildest form. Frostnip involves initial redness, a cold feeling, and numbness, but it does not cause permanent tissue damage and the skin remains soft.
As freezing continues, superficial frostbite affects the skin and underlying tissues, causing the skin to become white or waxy and feel hard to the touch, though the tissue underneath remains soft. After rewarming, fluid-filled blisters may appear within 12 to 36 hours. Deep frostbite is the most severe stage, affecting all layers of skin and tissues below, where the area becomes cold, hard, and completely numb. The skin may appear white, blue-gray, or mottled, and large, dark, hemorrhagic blisters can form 24 to 48 hours after rewarming, indicating deeper tissue destruction.
Hypothermia symptoms are categorized by the severity of the core temperature drop. Mild hypothermia (95°F to 89.6°F or 35°C to 32°C) is marked by the body’s attempt to generate heat, resulting in vigorous and uncontrollable shivering. The person may also experience slurred speech, confusion, and lack of coordination.
In moderate hypothermia (89.6°F to 82.4°F or 32°C to 28°C), shivering often stops as energy reserves are depleted. Mental status decreases significantly, leading to increased confusion, drowsiness, and poor judgment. Severe hypothermia (below 82.4°F or 28°C) is characterized by a loss of consciousness, unresponsiveness, and minimal or absent reflexes. The heart rate and breathing become dangerously slow, potentially leading to cardiac arrest.
Emergency Response and Re-warming Strategies
Emergency care for frostbite focuses on preventing further damage and initiating cautious re-warming. The affected area must be protected from trauma; it should not be rubbed or massaged, as this can worsen the tissue injury caused by ice crystals. The most effective initial treatment is rapid re-warming by immersing the area in a warm water bath, ideally between 100°F and 104°F (38°C and 40°C).
Rewarming should only be done if there is no risk of the tissue re-freezing before the patient reaches medical care, as a freeze-thaw-refreeze cycle causes more extensive damage. After re-warming, the skin may blister, swell, and become painful. The area should be loosely bandaged with dry, sterile dressings, with fingers and toes separated by gauze. Affected parts should not be used for walking or other activities, and professional medical attention must be sought immediately to manage the reperfusion injury and potential infection.
The emergency response for hypothermia prioritizes raising the core body temperature and stabilizing the patient. The individual must be moved out of the cold environment, and any wet clothing should be removed and replaced with dry insulating layers to stop further heat loss. Mild hypothermia can often be treated with passive re-warming, using blankets and covering the head to prevent heat escape.
For moderate cases, active external re-warming should be applied to the trunk, such as with warm packs placed on the chest and under the armpits, rather than the extremities. If the person is conscious and able to swallow, they can be given warm, non-alcoholic, non-caffeinated drinks. Vigorous movement should be avoided, as it can cause cold, acidic blood from the extremities to rush back to the core, potentially triggering a dangerous drop in core temperature and heart rhythm disturbances.