Contact Dermatitis
Overview
Contact dermatitis is an inflammatory skin reaction at a site of contact with an irritant or allergen (such as plants, metals, cosmetics, detergents, or medicines), presenting with sharply demarcated erythema, papules, vesicles, swelling, itching, or burning; allergic reactions may recur at lower exposure. In Chinese medicine acute cases are mostly a toxic-heat or damp-heat pattern with external evil invading the skin, while recurrent cases involve blood-heat or lingering wind-dampness.
TCM disease & pathogenesis
In TCM this is 'lacquer sore' (qi chuang), also called plaster wind, described as early as the General Treatise on Causes and Manifestations of All Diseases (Zhu Bing Yuan Hou Lun, 7th c.): 'Lacquer is toxic; some people are by constitution intolerant of it and are poisoned merely by contact'—an early recognition of individual susceptibility. The lesion lies in the skin and interstices and relates to the lung (which governs skin and body hair) and spleen (which governs flesh). The cause is contact with lacquer/drug toxins, pollen, metals, or damp-heat pathogen that attacks the exterior and contends with qi and blood in the skin, stagnating into heat; damp-heat steaming outward produces redness, swelling, itching, and weeping. Those with innate intolerance and weak defensive qi recur most easily. Patterns divide into external toxin attack and internal damp-heat accumulation; treatment clears heat, drains dampness, cools blood, resolves toxin, and expels wind to stop itching, while the contactant must be removed at once.
Pattern differentiation (clinical patterns)
Toxic-Heat with Dampness (Acute)
Abrupt onset with sheets of bright red hot skin, swelling and vesicles, weeping erosions, itching and burning pain, vexation and thirst, red tongue with yellow coating, rapid pulse.
Clear heat and drain dampness; cool the blood and resolve toxicity.
Blood Deficiency with Wind-Dryness (Chronic Recurrent)
Recurrent thickened rough lesions with scaling and fissures, itching worse at night, pallor, pale tongue with thin coating, fine pulse.
Nourish blood and moisten dryness; expel wind and stop itching.
Connections
Daily care & prevention
Immediately stop contact with and wash off the suspected substance; avoid scratching and hot-water or soap irritation; keep the area clean and dry and use cool wet compresses. Note new products, plants, metals, or occupational exposures. Massage Quchi (LI11), Hegu (LI4), Xuehai (SP10), and Sanyinjiao (SP6). Seek care for extensive blistering, facial/genital involvement, pus, fever, or no improvement within days.
When to seek medical care
Seek urgent care for rapidly spreading redness and swelling, severe blistering or skin shedding, pus and fever (infection), swelling of the face or airway with breathing difficulty (severe allergy), or involvement of the eyes.