Although there is no exact record of this disease name in the literature of Chinese medicine, many surgical works have discussed the clinical manifestations of contact dermatitis. It has different names depending on the substance causing the contact. For example, those caused by lacquer irritation are called "lacquer sore," those caused by plaster are called "plaster dermatitis," and those caused by contact with a chamber pot are called "chamber-pot dermatitis (contact dermatitis of buttock)," all of which fall under the category of this disease. It is believed that the onset of the disease is due to an inherent intolerance of the body, contact with certain "toxic" substances, the invasion of pathogenic toxins into the skin, which then stagnate and transform into heat, and the pathogenic heat interacting with qi and blood. For example, Zhubing Yuanhou Lun points out: "Lacquer is toxic, and some people have an inherent fear of lacquer, being poisoned just by seeing it... There are also those who are naturally tolerant, who can boil it all day without harm."

bubble_chart Modern Research

Contact dermatitis is an inflammation of the skin or mucous membrane that occurs at the site of contact with certain substances. It can be divided into primary irritant contact dermatitis (also known as toxic dermatitis, which is non-allergic) and allergic contact dermatitis caused by allergic reactions. Clinically observed contact dermatitis mainly belongs to the latter, so this section primarily discusses allergic contact dermatitis. The incidence of this disease is relatively high, ranking second only to infectious skin diseases in developing countries.

Substances that cause contact dermatitis include animal, plant, chemical, and daily-use items. Reports of contact with medications are also common, such as mercury agents, sulfonamides, antibiotics, and Chinese medicinals like Aconite Lateral Root, Dahurian Angelica, Medicinal Changium Root, Chinese Clematis Root, Sichuan Chinaberry Bark, moxa sticks, Jin Bu Huan Plaster, Wan Ying Plaster, Toxin-Removing Plaster, Qian Chui Plaster, Wu Yu Plaster, Five Flavors Dampness-Removing Powder, Pearl Powder, Miraculous Pill of Six Ingredients, and Hua Tuo Plaster. Although the exact immunological mechanism of contact dermatitis is not fully understood, extensive research has shown that it is a type of eczema-like sexually transmitted disease caused by a T-cell-mediated delayed hypersensitivity reaction.

The diagnosis of this disease is mainly based on clinical manifestations. Dermatitis generally presents as non-specific eczema-like lesions, with the severity of skin damage varying depending on the nature of the contact substance and individual reactivity. Acute cases may exhibit erythema, papules, edema, wheals, blisters, erosions, exudation, or ulcers; chronic cases may show scales, crusts, skin thickening, and lichenification. In addition to the local contact area, dermatitis can also occur in nearby or distant areas from the contact site. Common symptoms include itching, burning, or distending pain, and in severe cases, systemic reactions such as fever and chills, nausea, and headache may occur. The incubation period is about 4-5 days, and the onset time shortens upon re-exposure. The course of the disease is self-limiting, and with the removal of the disease cause and appropriate treatment, it generally resolves in about 1-2 weeks.

Based on medical history (contact history), the distribution and location of skin lesions, the diagnosis is generally not difficult and can be easily distinguished from eczema-like skin manifestations caused by other reasons. Patch testing is of significant value in confirming the diagnosis and identifying the allergen responsible for allergic contact dermatitis.

bubble_chart Pattern Analysis

1. Invasion of Wind-heat︰The onset is sudden, with aversion to cold accompanied by fever, irritability, generalized or localized papules, swelling, and unbearable cutaneous pruritus. The tongue appears reddish with thin yellow coating, and the pulse is floating and rapid. The treatment involves dispersing wind and clearing heat, removing toxins to relieve itching. Modified Wind-Dispersing Powder is prescribed, consisting of Schizonepeta, Saposhnikovia Root, Sophora, Atractylodes Rhizome, and Akebia Stem, 10 grams each, along with Cicada Slough and Spirodela, 6 grams each, and Gypsum, 30 grams (to be decocted first). If the rash presents with erosion and exudation, and the tongue coating is greasy, additional herbs such as Coptis Rhizome, 6 grams, Phellodendron Bark, 10 grams, Cnidium Fruit, 15 grams, and Dandelion, Glabrous Greenbrier, and raw Coix Seed, 30 grams each, may be included. For yellow urine and constipation, add Unprocessed Rehmannia Root and raw Rhubarb Rhizome (to be decocted later), 10 grams each, and Talc, 15 grams. For headache, add Mulberry Leaf and Chrysanthemum Flower, 10 grams each.
2. Toxic Heat︰Fever, irritability, red patches or swelling on the whole body or localized areas, or blisters, erosion, itching, burning sensation, dark urine, constipation. Red tongue with yellow and rough coating, rapid pulse. Clearing heat and removing toxin, dissipating ecchymosis, dissipating ecchymosis and removing toxin. Modified decoction: Gypsum 50g (to be decocted first), Anemarrhena, Gardenia, Scrophularia Root, Coptis Rhizome, Great Burdock Achene, Cimicifuga Rhizome, Bamboo Leaf, Rhubarb Rhizoma (to be decocted later) 10g each, Forsythia 15g. For chest stuffiness and anorexia with greasy coating, add Atractylodes Rhizome and Dried Tangerine Peel; for loose stools, remove Rhubarb Rhizoma; for headache and cutaneous pruritus, add Cicada Slough 6g, Mulberry Leaf and Chrysanthemum Flower 10g each; for scanty dark urine, add Plantain Herb and Talc 15g each; for erosive or exudative rashes, add Cnidium Fruit, Glabrous Greenbrier and Sophora 20g each.