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Nonfreezing Tissue Injuries

(Chilblains [Pernio]; Frostnip; Immersion Foot [Trench Foot])

By Daniel F. Danzl, MD, Professor and Chair, Department of Emergency Medicine, University of Louisville School of Medicine

In nonfreezing tissue injuries, parts of the skin are chilled but not frozen.

Nonfreezing tissue injuries include frostnip, immersion foot, and chilblains.


Frostnip is a cold injury in which the chilled areas of skin become numb, swollen, and red. The only treatment needed is warming the area for a few minutes. During warming, the area may hurt or itch intensely. No permanent damage results, although sometimes the area is particularly sensitive to cold for months or years afterward.

Immersion (trench) foot

Immersion foot (trench foot) is a cold injury that develops when a foot is kept in wet, cold socks and shoes or boots for several days. The foot is pale, clammy, swollen, numb, and cold. After warming, the foot becomes red and painful to the touch. Sometimes blisters develop, which may open and become infected. The skin may become overly sensitive to changes in temperature and to even the lightest touch, and this sensitivity may last for weeks. The foot may also become overly sweaty.

Treatment consists primarily of the following measures:

  • Gently warming, drying, and cleaning the foot

  • Elevating the foot

  • Keeping the foot dry and warm

Some doctors give antibiotics to prevent infection. A tetanus booster is given if the person’s tetanus vaccination is not current. Doctors sometimes give amitriptyline to help relieve sensitivity to pain and light pressure. Because nicotine impairs blood flow, avoiding nicotine may help.

Rarely, this type of injury occurs in the hands.

Immersion foot can often be prevented by wearing properly fitting shoes or boots, changing socks, and drying the feet at least daily.

Chilblains (pernio)

Chilblains (pernio) is an uncommon reaction that may occur with repeated exposure to dry cold. Symptoms include itching, pain, redness, swelling, and, in rare cases, discolored areas or blisters on the affected area (usually the front of the lower leg or the top surface of the fingers). The condition is uncomfortable and recurrent but not serious. Preventing exposure to cold is the best treatment. Nifedipine, limaprost, or corticosteroids, taken by mouth, sometimes relieve symptoms. Avoiding nicotine may help.

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