Passive rewarming is supported by Wilderness Medical Society (WMS 2023) guidelines
Active rewarming avoided — worsens ischemia-reperfusion and pain
Amitriptyline is the best-evidenced analgesic for NFCI neuropathic pain
Recommended in WMS 2023 and Zafren 2021 review
Should be initiated early when pain develops
Gabapentin is second-line with supporting case series data
Nifedipine — evidence does NOT support use in NFCI (unlike chilblains)
Iloprost — prostacyclin analog; limited evidence for severe vasospastic NFCI
Prevention evidence
Daily sock changes are the most effective preventive intervention
Military education programs have dramatically reduced incidence
Adequate nutrition and hydration reduce susceptibility
Avoidance of constrictive footwear and tobacco (vasoconstriction)
Patient Discharge Instructions
copy discharge instructions
What is immersion foot?
Immersion foot (also called trench foot) is a cold injury to the feet caused by prolonged exposure to cold, wet conditions
It is not frostbite — the skin does not freeze, but the nerves and blood vessels are damaged
Most mild cases recover fully with proper care, but severe cases can cause long-term nerve pain and cold sensitivity
Home care instructions
Keep your feet dry and warm at all times
Change into clean, dry socks at least once daily — more often if feet become wet
Do not apply heating pads, hot water bottles, or soak feet in warm water — this can worsen the injury
Elevate your feet above heart level when resting to reduce swelling
Do not rub or massage the affected feet
Wear well-fitting, non-constricting footwear
Inspect feet daily for any new blisters, sores, or skin breakdown
Medications
Take prescribed pain medications as directed — amitriptyline or gabapentin may be prescribed for nerve pain
Do not stop medications abruptly without talking to your doctor
Over-the-counter ibuprofen or naproxen can help with mild pain if no contraindication
Return to emergency department immediately if
Worsening pain despite medication
New or spreading redness, warmth, or swelling in the legs
Fever or chills
Foul-smelling discharge or pus from the skin
Inability to bear weight or walk
New blisters or open sores developing
Skin turning black or developing a dark color (gangrene concern)
Signs of whole-body illness — confusion, very rapid heart rate
Follow-up
Return for a wound check and pain reassessment in 2–3 days
Long-term nerve pain or cold sensitivity may require specialist follow-up
Notify your doctor if you notice increased sensitivity to cold in the future
References
Guidelines and key sources
Zafren K. Nonfreezing Cold Injury (Trench Foot). International Journal of Environmental Research and Public Health. 2021. PMID 34639782
Primary evidence base for staging, diagnosis, and management of NFCI
Supports amitriptyline as first-line analgesic for NFCI pain
Zafren K, Hollis S, Weiss EA, et al. Prevention and Treatment of Nonfreezing Cold Injuries and Warm Water Immersion Tissue Injuries. Wilderness and Environmental Medicine. 2023
Wilderness Medical Society Clinical Practice Guidelines supplement
Recommends passive rewarming; defines management of NFCI subtypes
Rathjen NA, Shahbodaghi SD, Brown JA. Hypothermia and Cold Weather Injuries. American Family Physician. 2019. PMID 31790182
Broad cold injury overview including NFCI; management principles
Cappaert TA, Stone JA, Castellani JW, et al. National Athletic Trainers' Association Position Statement: Environmental Cold Injuries. Journal of Athletic Training. 2008. PMID 19030143
Discusses susceptibility factors including racial differences and prior injury sensitization
Castellani JW, Young AJ, Ducharme MB, et al. ACSM Position Stand: Prevention of Cold Injuries During Exercise. Medicine and Science in Sports and Exercise. 2006
Prevention evidence base; footwear and sock change recommendations
Olson Z, Kman N. Immersion Foot: A Case Report. Journal of Emergency Medicine. 2015. PMID 26004855
Emergency department management perspective
Mistry K, Ondhia C, Levell NJ. A Review of Trench Foot: A Disease of the Past in the Present. Clinical and Experimental Dermatology. 2020. PMID 31309614
Historical context and contemporary clinical review
To MJ, Brothers TD, Van Zoost C. Foot Conditions Among Homeless Persons: A Systematic Review. PloS One. 2016. PMID 27936071
Epidemiology in homeless populations; up to 20% foot-related complaints
Backer HD, Freer L. Heat and Cold Illness in Travelers. CDC Yellow Book. 2025
Travel medicine perspective; warm water and cold immersion foot distinction
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.