Chilblains refer to relatively severe localized inflammatory skin damage caused by cold. They are a type of non-freezing cold injury that occurs in low-temperature, humid regions during winter or early spring, commonly seen in the Yangtze River basin, primarily affecting areas such as hands, feet, earlobes, and the tip of the nose. Characterized by a prolonged course and recurrent episodes, chilblains cause burning itch and hot pain in affected areas, significantly impacting work and rest.

I. Causes

The formation of chilblains involves both intrinsic and extrinsic factors. Intrinsic factors mainly include the body's functional state, such as skin blood vessel sensitivity to cold, autonomic nervous system function, and genetic predisposition. Extrinsic factors primarily involve environmental temperature, humidity, and protective measures. Moisture accelerates body surface heat loss, so regions with high winter humidity, particularly where temperatures drop below 10°C, experience higher incidence rates of chilblains.

Additionally, autonomic dysfunction, poor peripheral circulation, excessive sweating in hands and feet, lack of exercise, tight shoes or socks, malnutrition, anemia, and certain chronic wasting diseases often serve as predisposing factors for chilblains.

II. Pathogenesis

The mechanism by which cold causes chilblains remains unclear. It may be related to hypersensitivity of cutaneous blood vessels to cold, or possibly associated with autonomic nervous system dysfunction and genetic factors.

During moderate cold exposure, healthy individuals typically experience initial cutaneous vasoconstriction followed by vasodilation to maintain blood perfusion. In patients with chilblains, however, persistent spasmodic contraction occurs in the thicker cutaneous arterioles alongside persistent dilation of thinner superficial vessels, leading to blood stasis and local tissue hypoxia that causes cellular damage. Prolonged duration of this condition alters intracellular and extracellular environments, potentially resulting in paralytic vasodilation, venous congestion, increased vascular permeability, and plasma leakage into interstitial spaces causing edema.

III. Clinical Classification

Cold injuries caused by low temperatures are categorized into two types: non-freezing cold injury and freezing cold injury. Non-freezing cold injury results from exposure to temperatures below 10°C but above freezing, combined with damp conditions, such as chilblains, trench foot, and immersion foot. Chilblains are a type of non-freezing cold injury, which can be classified into the following three degrees based on severity.

Degree I (erythematous chilblains): Superficial skin involvement. The affected skin turns pale, followed by redness and swelling, possibly accompanied by localized itching, stinging, or paresthesia.

Degree II (vesicular chilblains): Full-thickness skin involvement. The damage extends to the deeper layers of the skin, with prominent local swelling and the formation of blisters containing serous or bloody fluid. Severe pain is present; the blisters dry within days, forming a black eschar over 2–3 weeks, which eventually sheds as the wound heals.

Degree III (necrotic chilblains): Involvement of skin and subcutaneous tissues. The injury reaches the deep layers of the skin, subcutaneous tissue, or even muscles and bones. Blisters typically appear 3–7 days post-injury, with the affected area turning purplish-black and surrounding tissues becoming edematous. Pain is intense, and limb mobility is restricted. Dry gangrene usually develops after about 7 days, with complete loss of sensation and function; wound healing is slow. After 2–3 weeks, necrotic tissue separates from healthy tissue, often leaving scars and functional impairment.

The most severe form of frostbite is generalized hypothermia, which refers to systemic frostbite caused by extreme cold or prolonged exposure to low temperatures. In the early stages of generalized frostbite, symptoms include shivering, pale and cold skin, accelerated breathing and heart rate, sluggish response, mental confusion, stiffness in all muscles and joints, ultimately leading to respiratory and circulatory failure. Without prompt emergency treatment, this condition is often life-threatening.

IV. Western Medication Treatment

Current Western medications for frostbite treatment mainly fall into three categories: vasodilators, anticoagulants, and anti-inflammatory drugs. For instance, scopolamine can expand capillaries and improve microcirculation. Clinical reports indicate that an ointment made by grinding scopolamine tablets and mixing them with green ointment, when applied topically to the affected area and taken orally, has a treatment efficacy rate as high as 98%. Nifedipine functions to dilate blood vessels and enhance skin microcirculation. Dexamethasone has anti-infection and antipruritic effects. Meanwhile, nitrofurazone possesses antibacterial and anti-inflammatory properties for treating erosions and inflammatory infections caused by frostbite.

V. Traditional Chinese Medicine Treatment

According to Traditional Chinese Medicine, this condition occurs due to insufficient yang energy in the patient and invasion by external cold-damp pathogens, leading to impaired circulation of qi and blood, resulting in blood stasis and obstruction that causes the disease.

He Huiying et al. developed a compound frostbite cream using ingredients such as Angelica sinensis, Asarum sieboldii, Cinnamomum cassia, Zingiber officinale, borneol, vitamin E, and cream base. In a study of 90 frostbite cases, the treatment showed ≥60% marked effectiveness after 10 days, 30%-59% effectiveness, and <30% ineffectiveness.

Ai Dongfang's self-made Mayinglong Musk Hemorrhoid Ointment (containing musk, pearl, bezoar, calamine, borax, and borneol) was applied to the affected area. Among 46 cases of this disease, 35 were cured, accounting for 76%; 11 were effective, accounting for 24%. The total effective rate was 100%.

Liu Jingwei et al. formulated a compound traditional Chinese medicine chilblain wash (composed of Magnolia Flower, Angelica Dahurica, Safflower, Nardostachys, Kaempferia, Aconite, and Dried Ginger) for topical application on affected areas. In a study of 320 cases with this condition, one treatment course lasted 5 days. The cure rate reached 79% after one course and 100% after two courses of treatment.

6. Physical Therapy

(1) He-Ne Laser Therapy

He-Ne laser can improve vascular function, as weak laser irradiation has a vasodilatory effect that enhances microcirculation in affected areas. It increases blood oxygen-carrying capacity, leading to improved tissue oxygenation which helps maintain and restore normal metabolism. Simultaneously, it reduces blood viscosity, preventing blood stasis, occlusion, and thrombosis in capillaries. Since chilblains are generally caused by cold-induced vasomotor dysfunction, microcirculatory disorders, and tissue hypoxia, He-Ne laser therapy demonstrates good therapeutic efficacy for chilblain treatment.

(2) Infrared therapy

The therapeutic effect of infrared radiation is based on its thermal properties. Under infrared irradiation, tissue temperature rises, capillaries dilate, blood flow accelerates, metabolism increases, and the vitality and regenerative capacity of tissue cells improve. Additionally, infrared rays can reduce nervous system excitability and provide analgesic effects. For frostbite with existing ulcerations, it helps improve tissue nutrition, eliminate granulation edema, promote granulation tissue growth, and accelerate wound healing.

(3) Acupuncture Therapy

Acupuncture at the Zhongwan (CV12) acupoint can enhance gastric motility and thicken the folds of the jejunal mucosa, thereby improving the digestion and absorption of nutrients to facilitate the healing of frostbite. Needling the Hegu (LI4), Waiguan (TE5), and Houxi (SI3) acupoints helps unblock yang qi in the hands, producing a warming effect on the hands.

7. Other Diseases That Can Cause Chilblains

If chilblains recur frequently and persist for a long time without healing, other diseases should also be considered. Literature reports indicate that malnutrition and emaciation due to celiac disease can cause chilblains, possibly because patients with anorexia nervosa exhibit increased peripheral vascular reactivity to cold and impaired thermoregulation.

Among autoimmune diseases prone to triggering chilblains, systemic lupus erythematosus (SLE) is predominant, as SLE patients are more susceptible to chilblains in cold environments.

Additionally, some data suggest that acute episodes of chronic myelogenous leukemia and breast cancer metastases may initially present with skin chilblains or chilblain-like changes. A foreign case report documented a 6-year-old female patient with monocytic leukemia who had recurrent chilblain-like lesions on her toes for an extended period.