Frostbite is a freezing injury caused by ice crystal formation in tissues exposed to subfreezing temperatures, resulting in cellular damage, microvascular thrombosis, and progressive ischemia that can lead to tissue necrosis and amputation. [1-2] The following is a clinically organized summary for emergency medicine and primary care management.
The NEJM review by Sheridan et al. illustrates the spectrum of frostbite severity, from superficial blistering with tissue salvage to deep necrotic injury requiring amputation:
1. History
- Mechanism and exposure: Duration, temperature, wind chill, altitude, wet vs. dry cold, contact with cold metal/liquids [3]
- Timing: When did exposure begin? When was tissue last warm? When was rewarming initiated? Estimate warm-ischemia time (time since thawing) — critical for thrombolytic eligibility [1-2]
- Symptom progression: Initial numbness/tingling → loss of sensation → pain with rewarming → blister formation [2][4]
- Refreezing: Was the tissue thawed and then refrozen? Freeze-thaw-refreeze injury is significantly worse than prolonged freezing [1][5]
- Field treatment: Any rewarming attempted? NSAIDs given? Aspirin? Walking on frostbitten feet?
- Associated symptoms: Shivering, confusion, altered mental status (suggests concurrent hypothermia) [5]
2. Alarm Features
- Hemorrhagic blisters or cyanosis without blister formation → deep tissue infarction (3rd/4th degree) [2][6]
- Absent capillary refill or absent Doppler signals in distal digits after full rewarming [1]
- Hard, waxy, insensate tissue that remains firm after rewarming [2][7]
- Concurrent hypothermia (core temp <35°C) — treat core hypothermia first; extremity rewarming can paradoxically drop core temperature [5]
- Altered mental status — evaluate for head trauma, intoxicants, hypothermia [1]
- Compartment syndrome post-thaw from reperfusion edema [4]
- Injury extending proximal to the proximal interphalangeal (PIP) joints — triggers consideration for thrombolysis/iloprost [2]
3. Medications
Acute Treatment
- Ibuprofen 400 mg PO BID (12 mg/kg/day divided BID) — antiprostaglandin effect, limits inflammatory damage; continue until healing or surgery [2][8]
- Aspirin 75–250 mg — antiplatelet effect, can be given in the field [8]
- Opioid analgesics — rewarming is intensely painful; provide adequate analgesia [2][6]
- Topical aloe vera every 6 hours — antiprostaglandin activity [2][8]
- Tetanus prophylaxis — administer per guidelines [2][4]
Advanced/Hospital Therapies
- Iloprost (Aurlumyn, FDA-approved February 2024) — IV prostacyclin analogue; first-line for Grade 3–4 frostbite within 48–72 hours of injury; 0.5–2 ng/kg/min IV for 6 hours/day for up to 8 days [2][6][9]
- tPA — IV or intra-arterial; for deep frostbite with absent distal perfusion and warm-ischemia time <24 hours; IV dosing: 0.15 mg/kg bolus then 0.15 mg/kg/h for 6 hours + heparin. Each hour of delay reduces salvage rate by ~28% [2][4]
Contraindicated/Cautions
- Avoid rubbing or massaging frostbitten tissue [2]
- Avoid dry heat (heating pads, fires) — risk of thermal burn on insensate tissue
- Avoid smoking — vasoconstriction worsens ischemia [1]
- QT-prolonging drugs should be avoided in concurrent hypothermia [10]
- Antibiotic prophylaxis is generally unnecessary — frostbite is not inherently infection-prone [4]
4. Diet
- Hydration — oral or IV rehydration is important, especially in dehydrated, hypothermic, or high-altitude patients [8]
- Adequate caloric intake — poor nutrition and dehydration are predisposing factors [3]
- No specific dietary triggers; focus on maintaining normothermia and adequate nutrition during recovery
5. Review of Systems
- Constitutional: Shivering, fatigue, confusion (hypothermia)
- Neurologic: Numbness, paresthesias, loss of sensation, cognitive impairment
- Cardiovascular: Chest pain, palpitations (arrhythmia risk with hypothermia)
- Musculoskeletal: Joint stiffness, inability to move digits
- Psychiatric: Substance use history, psychiatric comorbidities (common in urban frostbite populations) [1]
- Skin: Color changes (white → waxy → blue/purple → black), blister character (clear vs. hemorrhagic)
6. Collateral History and Family History
- Collateral: Witnesses to exposure duration, ambient conditions, intoxicant use, mental status changes, field rewarming attempts
- Social context: Homelessness, outdoor occupation, military service, mountaineering, substance use — all major contributors [1][3]
- Family history: Raynaud's phenomenon or other vasospastic disorders may increase susceptibility [3][7]
7. Risk Factors
8. Differential Diagnosis
- Frostnip — superficial nonfreezing injury; numbness and pallor resolve quickly with rewarming; no tissue loss [2][4]
- Nonfreezing cold injury (trench foot/immersion foot) — occurs at 0–15°C in wet conditions; erythema, cyanosis, mottling; avoid rapid active rewarming [6-7]
- Pernio (chilblains) — erythrocyanotic papules with pruritus/pain after cold/wet exposure; self-limited [6-7]
- Raynaud's phenomenon — bilateral blanching with rapid recovery after rewarming; no tissue loss [7]
- Pressure injury/compartment syndrome — can coexist with cold injury; painful ischemia from swelling in constrictive clothing [7]
- Peripheral arterial disease — chronic ischemia; distinguish by history and vascular exam
- Cellulitis/necrotizing soft tissue infection — unilateral redness/swelling with systemic symptoms; usually not limited to distal extremity [7]
9. Past Medical History
- Previous frostbite — increases vulnerability to future cold injury and worsens outcomes [3][6]
- Peripheral vascular disease, diabetes, peripheral neuropathy — impair perfusion and sensation [3]
- Raynaud's phenomenon — predisposes to vasospasm [3]
- Psychiatric illness, substance use disorders — common in urban frostbite populations; affect compliance and follow-up [1]
- Recent surgery, stroke, trauma — contraindications to thrombolytic therapy [2]
10. Physical Exam
Vital Signs
- Core temperature (rectal or esophageal preferred) — rule out concurrent hypothermia [1][5]
- Bradycardia, hypotension may indicate hypothermia
Focused Exam
- Before rewarming: Tissue appears pale, white, yellow, or blue; firm/hard and waxy; insensate [2][7]
- After rewarming — classify severity:
- 1st degree: Erythema, edema, white/yellow plaque; no blisters [2]
- 2nd degree: Clear or milky fluid-filled blisters with surrounding erythema [2]
- 3rd degree: Hemorrhagic blisters — indicates injury into reticular dermis [2]
- 4th degree: Cyanosis, no blisters, no capillary refill; necrosis into muscle/bone [2][6]
- Distal perfusion assessment: Capillary refill, Doppler signals in distal pulp, pulse oximetry of digits [1]
- Evaluate for compartment syndrome (tense compartments, pain with passive stretch) [4]
- Examine for concomitant trauma
11. Lab Studies
- CBC, BMP, coagulation studies — baseline, especially if considering thrombolysis
- Lactate — if concern for systemic hypothermia or tissue ischemia
- Blood alcohol level, urine drug screen — if altered mental status [1]
- Type and screen — if thrombolysis planned (bleeding risk)
- CK — if concern for rhabdomyolysis from prolonged exposure/immobility
- Frostbite is not inherently infection-prone; routine cultures are not indicated unless signs of secondary infection develop [4]
12. Imaging
- First-line (for deep frostbite): Tc-99m pyrophosphate scintigraphy or MR angiography — predicts tissue viability 4–24 hours after thawing; guides surgical planning [4][6]
- Digital subtraction angiography — used pre-thrombolytic intervention and to monitor progress [2][11]
- Plain radiographs — if concern for underlying fracture or late-stage bony involvement
- Imaging is unnecessary for superficial (1st/2nd degree) frostbite with intact perfusion after rewarming [6]
13. Special Tests
- Doppler ultrasound of distal pulp — assess small-vessel perfusion after rewarming [1]
- Transmission pulse oximetry of individual digits — quick bedside perfusion check [1]
- Cauchy grading system — 4-tier classification based on clinical and imaging findings after rewarming [2]
- Simplified 2-tier field classification: Superficial (1st–2nd degree) vs. Deep (3rd–4th degree) — more practical before imaging [2][6]
14. ECG
ECG is indicated when concurrent hypothermia is suspected. Frostbite alone does not produce ECG changes, but coexisting hypothermia produces characteristic findings: [12-13]
- Osborn (J) waves — positive deflection at QRS-ST junction; amplitude correlates with degree of hypothermia; present in ~53% of hypothermic patients [12][14]
- QT prolongation — present in ~49% of hypothermic patients [12]
- PR prolongation and QRS widening [13][15]
- Sinus bradycardia, atrial fibrillation (up to 21–50%) [12][16]
- VF/pulseless VT — 2.4% of hypothermic patients; risk highest at moderate hypothermia (~31°C) [12][17]
- Osborn waves can mimic ST-elevation MI — avoid unnecessary cath lab activation [13-14]
15. Assessment
Severity Stratification (after rewarming)
- Superficial (1st–2nd degree): Favorable prognosis; erythema, edema, clear blisters; tissue salvage expected [2][6]
- Deep (3rd–4th degree): Hemorrhagic blisters, cyanosis, absent perfusion; high risk of tissue loss and amputation [2][6]
Key Clinical Pearls
- Severity is difficult to assess before rewarming — frozen tissue all looks similar (hard, pale, anesthetic) [2]
- Full demarcation of necrosis may take up to 3 months — "frostbitten in January, amputate in July" [4]
- The pathophysiology involves 4 overlapping phases: prefreeze → freeze-thaw → vascular stasis → late ischemic, with microvascular thrombosis as the primary driver of tissue loss [2]
Complications
- Amputation, compartment syndrome, secondary infection, rhabdomyolysis
- Long-term: chronic neuropathic pain, cold hypersensitivity, vasomotor disturbances, frostbite arthritis, epiphyseal damage in children [1][18]
16. Treatment Plan
Pre-Hospital / Field
- Remove from cold exposure; remove wet/constrictive clothing and jewelry [5]
- Do NOT rewarm if risk of refreezing — freeze-thaw-refreeze is worse [1][5]
- Protect tissue — do not rub, walk on frostbitten feet if avoidable [5]
- If sustained thaw can be assured: rewarm in 37–39°C water for 20–30 minutes until tissue is soft and pliable [2][5-6]
- Ibuprofen 400 mg PO and aspirin 75–250 mg if available [8]
- Bulky, loose, dry dressings; elevate extremity [5]
Hospital — Initial Management
- Treat hypothermia first (core rewarming takes priority) [2][5]
- Rapid rewarming in 37–39°C water bath ~30 minutes [2]
- Ibuprofen 12 mg/kg/day divided BID [2]
- Aggressive pain management (opioids as needed) [2]
- Tetanus prophylaxis [2]
- Topical aloe vera every 6 hours [2]
- Clear blisters: selectively aspirate/debride; hemorrhagic blisters: leave intact [2]
- Dry, bulky dressings; elevate; air dry (never rub) [2]
Advanced Therapies (Grade 3–4)
- Iloprost (Aurlumyn): First-line for Grade 3–4 frostbite within 48–72 hours of injury; FDA-approved 2024 [2][6][9]
- tPA: Consider for deep frostbite at/proximal to DIP joint with absent perfusion and warm-ischemia time <24 hours; especially if iloprost unavailable [2]
- Angiography for pre-thrombolytic assessment and monitoring [2]
17. Disposition
Admit
- Deep frostbite (3rd–4th degree) — especially if thrombolysis or iloprost is being considered [2]
- Concurrent hypothermia requiring active rewarming [5]
- Altered mental status, significant trauma, or intoxication [1]
- Frostbite involving deeper tissue depths may require transfer to a burn center [5]
Discharge (with close follow-up)
- Superficial frostbite (1st–2nd degree) with intact perfusion after rewarming, adequate pain control, and reliable follow-up [6]
- Prescribe ibuprofen, aloe vera, wound care supplies
Consult
- Burn surgery/plastic surgery — for deep frostbite, potential amputation planning
- Vascular surgery/interventional radiology — if thrombolysis indicated [1-2]
- Social work — for homeless patients, substance use, psychiatric comorbidities [1]
18. Follow Up / Return Precautions
- Follow-up timing: 24–48 hours for wound reassessment; then weekly until healing or surgical planning [4]
- Tissue demarcation: Full necrotic demarcation takes up to 3 months — avoid premature amputation unless sepsis develops [4][8]
- Return precautions: Increasing pain, fever, purulent drainage, expanding erythema (infection), worsening discoloration, new numbness
- Long-term sequelae: Persistent cold sensitivity, neuropathic pain, paresthesias, frostbite arthritis; increased vulnerability to future cold injury [1][18]
- Neuropathic pain management: Gabapentinoids, amitriptyline, duloxetine; botulinum toxin injections have been used for refractory vasospasm and neuropathic pain [1][18]
- Patient counseling: Strict cold avoidance, smoking cessation, appropriate layered clothing, early recognition of frostnip as a warning sign [1-2]
- Children: Monitor for epiphyseal cartilage damage and growth disturbances [18]
References
1. Diagnosis and Treatment of Frostbite. — Sheridan RL, Goverman JM, Walker TG. The New England Journal of Medicine. 2022.
2. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update. — McIntosh SE, Freer L, Grissom CK, et al. Wilderness & Environmental Medicine. 2024.
3. ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance During Cold-Weather Exercise. — Castellani JW, Eglin CM, Ikäheimo TM, et al. Current Sports Medicine Reports. 2021.
4. Frostbite: Recommendations for Prevention and Treatment from the Wilderness Medical Society. — American Academy of Family Physicians (2020). 2020.
5. 2024 American Heart Association and American Red Cross Guidelines for First Aid. — Hewett Brumberg EK, Douma MJ, Alibertis K, et al. Circulation. 2024.
6. Heat and Cold Illness in Travelers. — Howard D. Backer and Luanne Freer CDC Yellow Book. 2025.
7. Prevention and Treatment of Nonfreezing Cold Injuries and Warm Water Immersion Tissue Injuries: A Supplement to the Wilderness Medical Society Clinical Practice Guidelines. — Zafren K, Hollis S, Weiss EA, et al. Wilderness & Environmental Medicine. 2023.
8. Interventions for Frostbite Injuries. — Lorentzen AK, Davis C, Penninga L. The Cochrane Database of Systematic Reviews. 2020.
9. FDA Drug Label. — Updated date: 2025-01-01. Food and Drug Administration.
10. Hypothermia and Cardiac Electrophysiology: A Systematic Review of Clinical and Experimental Data. — Dietrichs ES, Tveita T, Smith G. Cardiovascular Research. 2019.
11. What Interventional Radiologists Need to Know About Managing Severe Frostbite: A Meta-Analysis of Thrombolytic Therapy. — Lee J, Higgins MCSS. AJR. American Journal of Roentgenology. 2020.
12. Electrocardiographic Patterns of Accidental Hypothermia. — Okumura H, Okada N, Hamanaka K, et al. The American Journal of Emergency Medicine. 2025.
13. Electrocardiographic Manifestations of Hypothermia. — Mattu A, Brady WJ, Perron AD. The American Journal of Emergency Medicine. 2002.
14. Electrocardiography Unmasking the Cause of Unexplained Coma. — Rajendran G, Mahalingam S, Ramkumar A. JAMA Internal Medicine. 2026.
15. Hypothermia: Evaluation, Electrocardiographic Manifestations, and Management. — Aslam AF, Aslam AK, Vasavada BC, Khan IA. The American Journal of Medicine. 2006.
16. Update to Practice Standards for Electrocardiographic Monitoring in Hospital Settings: A Scientific Statement From the American Heart Association. — Sandau KE, Funk M, Auerbach A, et al. Circulation. 2017.
17. Moderate but Not Severe Hypothermia Causes Pro-Arrhythmic Changes in Cardiac Electrophysiology. — Dietrichs ES, McGlynn K, Allan A, et al. Cardiovascular Research. 2020.
18. Long-Term Sequelae of Frostbite-a Scoping Review. — Regli IB, Strapazzon G, Falla M, Oberhammer R, Brugger H. International Journal of Environmental Research and Public Health. 2021.