Whid chill chart
  • Results from the freezing of tissue
  • It is a disease of morbidity, not mortality
  • Risk correlated with temperature and wind speed
    • Risk is <5% when ambient temperature (includes wind chill) is > –15°C (5°F)
    • Most often occurs at ambient temperature < –20°C (–4°F)
  • Wetness and humidity increase the risk (water has 25x thermal conductivity of air)
  • Can develop within 2-3sec when metal surfaces that are at or below –15°C (5°F) are touched
  • Most commonly affects distal part of extremities, face, nose, and ears
  • High-risk groups: outdoor workers, elderly, homeless, drug or alcohol abusers, psychiatric disease, high-altitude or cold-weather athletes, military personnel
  • "Hunter's response" - prolonged repeated exposure to cold is protective


  • Freezing alone is usually not sufficient to cause tissue death
    • Thawing contributes markedly to the degree of injury
    • Endothelial damage, beginning at the point of thaw, is the critical event in frostbite
      • Resulting damage results in swelling, platelet aggregation, vessel thrombosis

Zones of Injury

  1. Zone of Coagulation
    • Most severe and usually most distal
    • Damage is irreversible
  2. Zone of Stasis
    • Middle zone characterized by severe, but possibly reversible, cell damage
    • It is this zone for which treatment may have benefit
  3. Zone of Hyperemia
    • Least severe and usually most proximal
    • Generally recovers without treatment in <10d

Clinical Features


Visual determination of tissue viability is difficult in first few weeks; classify early injuries as superficial or deep

Degree First (frostnip) Second Third Fourth
Pathophys Partial-skin freezing Full-thickness skin freezing Tissue loss involving entire thickness of skin Extension into subcutaneous tissues, muscle, bone, and tendon; little edema
Symptoms Stinging and burning, followed by throbbing Numbness followed by aching and throbbing Extremity feels like a "block of wood" followed by burning, throbbing, shooting pains Deep, aching joint pain
Course Numbness, erythema, swelling, dysesthesia, desquamation (days later)

Substantial edema over 4-6 hours; skin blisters form within 6-24 hours; Desquamate and form hard black eschars over several days

Hemorrhagic blisters form and are associated with skin necrosis and blue-gray discoloration Skin is mottled with nonblanching cyanosis and formation of deep, dry, black eschar
Pain with rewarming Minimal Mild to moderate Severe None
Prognosis Excellent Good Often poor Extremely poor
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Differential Diagnosis

Cold injuries


Second degree frostbite progression.
  • Usually clinical


  • If hypothermia present, must rewarm to a core temperature of at least 35°C before treating frostbite[1]
  • Remove all wet or constrictive clothing
  • Thawing
    • Do NOT attempt until the risk of refreezing is eliminated
      • Refreezing will cause even more severe damage
    • Rapid rewarming is the core of therapy and should be initiated as soon as possible
      • Extremities
        • Place in water with temperature of 37 to 39°C (98.6 to 102.2°F)
        • Approximately 20-30min, until extremity is pliable and erythematous
        • OR consider 38-40°C in whirlpool bath with antibacterial soap[2]
      • Face
        • Apply moistened compresses soaked in warm water
  • Analgesia
    • Rewarming is very painful
    • Provide parenteral opioids
  • Local wound care
    • Apply topical aloe vera cream q6hr (interrupts arachidonic acid cascade)
    • Affected digits should be separated with cotton and wrapped with sterile, dry gauze
    • Elevate involved extremities
    • Blister removal is controversial
      • Consider drainage of nonhemorrhagic bullae that interfere with movement
      • Never debride hemorrhagic bullae
    • Compartment Syndrome is a known complication; maintain a high suspicion
  • Systemic care
    • Ibuprofen may be helpful in interrupting arachidonic cascade
    • tPA or IV Iloprost (not available in US), followed by several days of heparin, reduces digit amputation rate for 3rd and 4th degree frostbite[3]
    • Hyperbaric oxygen therapy is of theoretical benefit but no randomized trials have been performed
  • Tetanus
    • Reported complication of frostbite; provide prophylaxis
  • Antibiotics
    • Controversial
    • Penicillin G 500,000 units IV Q6 hours for 48-72 hours
    • Topical bacitracin may be as good or better than IV penicillin
    • Silver sulfadiazine cream not consistently beneficial
      • May interact with aloe vera cream
  • Surgery
    • May be required if wet gangrene or infection occurs
    • Usually not performed until full demarcation occurs (3-4wk)


  • Patients with superficial local frostbite may be discharged home if social circumstances allow
  • Significant injuries will require ICU admission


  • Up to 65% of patients with frostbite experience sequelae from their injuries
    • Hypersensitivity to cold, pain, ongoing numbness
    • Arthritis, bone deformities, scars, and skin and nail dystrophia

See Also

External Links


  1. Handford C, Thomas O, Imray CHE. Frostbite. Emerg Med Clin N Am. 2017;35(2):281–299.
  2. Crawford-Mechem C et al. Frostbite Treatment & Management. Aug 25, 2015.
  3. Bruen KJ et al. Reduction of the incidence of amputation in frostbite injury with thrombolytic therapy. Arch Surg. 2007;142(6):546