Practice Guidelines

Frostbite: Recommendations for Prevention and Treatment from the Wilderness Medical Society


Am Fam Physician. 2020 Apr 1;101(7):440-442.

Author disclosure: No relevant financial affiliations.

Key Points for Practice

• To prevent worsening tissue damage, a frostbitten extremity should be rewarmed only if there is no risk of refreezing.

• Rapid rewarming via water bath immersion and intravenous low-molecular-weight dextran leads to improved outcomes in frostbite.

• To limit tissue loss, oral ibuprofen should be started as soon as available and continued until surgery or complete healing.

• Tissue plasminogen activator improves outcomes for deep frostbite extending to proximal interphalangeal joints if given within 24 hours.

From the AFP Editors

Frostbite is divided into four overlapping phases: prefreeze, freeze-thaw, vascular stasis, and late ischemic. The prefreeze phase consists of tissue cooling, which leads to vasoconstriction and ischemia without ice crystal formation. In the freeze-thaw phase, ice crystals form intracellularly during rapid-onset freezing or extracellularly during a slower freeze. Thawing leads to ischemia, reperfusion injury, and an inflammatory response. In the vascular stasis phase, vessels fluctuate between dilation and constriction. The late ischemic phase involves progressive tissue ischemia and infarction from a cascade of events: inflammation, intermittent vasoconstriction, reperfusion injury, emboli in microvessels, and thrombus formation in larger vessels.

First-degree frostbite causes numbness, erythema, and often edema. White or yellow, slightly raised plaque develops over injured areas. Second-degree frostbite causes erythema, edema, and superficial skin blisters. Third-degree frostbite causes deeper hemorrhagic blisters, indicating that the injury has extended into the reticular dermis and beneath the dermal vascular plexus. Fourth-degree frostbite extends completely through the dermis and involves comparatively avascular subcutaneous tissues, with necrosis extending into muscle and bone.

Frostnip is a superficial nonfreezing cold injury associated with intense vasoconstriction in exposed skin, usually the cheeks, ears, or nose. Ice crystals can form on skin surfaces, but not within the tissue. Numbness and pallor resolve quickly after warming, and no long-term damage occurs.


The following measures can minimize the risk of frostbite:

  • Protecting skin from moisture, wind, and exposure to cold

  • Avoiding perspiration or wet extremities

  • Increasing insulation and skin protection (e.g., adding layers of clothing, wearing mitts instead of gloves)

  • Using supplemental oxygen in extremely hypoxic conditions (above 25,000 ft [7,500 m])

  • Avoiding alcohol, illicit drugs, or medications that reduce perfusion

  • Avoiding cold weather exposure during illness

  • Using chemical or electric hand and foot warmers

  • Avoiding the use of skin emollients, which do not protect against frostbite and may actually increase risk

  • Maintaining adequate hydration and nutrition

  • Minimizing blood flow constriction caused by tight clothing or footwear

  • Minimizing duration of exposure to cold

  • Frequently assessing

Author disclosure: No relevant financial affiliations.

Coverage of guidelines from other organizations does not imply endorsement by AFP or the AAFP.

This series is coordinated by Sumi Sexton, MD, editor-in-chief.

A collection of Practice Guidelines published in AFP is available at



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