bubble_chart Concept

Although there is no explicit record of "drug rash" in Chinese medicine literature, discussions on drug reactions can be traced back to works such as Zhubing Yuanhou Lun, Qianjin Fang, and Waike Zhengzong. These reactions are generally referred to as "Chinese medicinals toxicity." For example, Zhubing Yuanhou Lun states: "All drugs that are said to be toxic or highly toxic can cause disturbances, harm humans, and even kill." In modern times, Chinese medicine has conducted research on drug rashes caused by drug allergies, proposing that the disease mechanism involves innate susceptibility to internal invasion by pathogenic toxins, or spleen dampness failing to transform, leading to dampness-heat accumulation, or the interaction of wind, dampness, and heat, compounded by drug toxicity. Dampness-heat toxins stagnate in the skin, or over time transform into fire, causing reckless movement of blood heat that spills over to the surface. In severe cases, the toxins become excessive, leading to blazing of both qi and blood, affecting the nutrient-blood, and attacking the zang-fu organs. Over time, yin fluids are depleted, yin impairment affects yang, and critical conditions may arise.

bubble_chart Modern Research

Drug rash, also known as drug-induced dermatitis, refers to the inflammatory reaction caused by drugs entering the human body through oral administration, injection, inhalation, topical application, etc., on the skin and mucous membranes. Its clinical manifestations are diverse; the same drug can cause different symptoms in different individuals, and the same clinical manifestation can be caused by different drugs. Generally, drug rash appears 7 to 10 days after medication through sensitization, but in patients who have previously used similar drugs, it can rapidly appear within hours or 1 to 2 days after re-administration. Common skin manifestations of drug rash include the following types: urticaria and angioedema type, scarlet fever-like or measles-like eruption type, exfoliative dermatitis or erythroderma type, bullous epidermal necrolysis type, fixed drug rash type, erythema multiforme type, purpura type, systemic contact dermatitis type, photosensitive dermatitis type, lichen planus-like rash type, acneiform eruption type, and vasculitis type, with the fixed drug rash type being more common and the bullous epidermal necrolysis type being the most severe. In addition to skin rashes, some drug rashes may be accompanied by systemic symptoms, with itching being the most common and obvious systemic symptom. In severe cases, it can affect various systems of the body.

Many types of drugs can cause drug rash, commonly including the following four categories:

1. Antipyretic analgesics: among which pyrazolone and salicylate preparations are common.
2. Sulfonamides: among which long-acting sulfonamides are more common.
3. Hypnotics and sedatives: among which barbiturates are more common.
4. Antibiotics: among which penicillin is more common.

Others such as antiserum, phenytoin-type antiepileptic drugs, nitrofurans, and phenothiazines can also cause it. Additionally, some Chinese herbal medicines have been reported to cause drug rash, such as Pueraria Root, smallpox powder, Arnebia, Dyers Woad, Isatis Root, Heartleaf Houttuynia Herb, pubescent holly root and stem, common andrographis herb, climbing groundsel herb, Tribulus terrestris, Fritillaria Bulb, decumbent bugle herb, Sophora Flower, Taiwan beautyberry leaf, Salvia, Carthamus, Ginseng, cuttlebone sepium, Earthworm, Shiny leaf Pricklyash Root, Rhubarb Rhizoma, Schisandra Fruit, etc., as well as single herbs and formulations like Miraculous Pill of Six Ingredients, Yunnan Baiyao, Cow-Bezoar removing toxin tablets, Shuangjie Pills, Lingqiao removing toxin tablets, Yimu Gao, compound Bupleurum injection, compound Earthworm injection, Isatis Root injection, common andrographis herb injection, etc.

The pathogenesis of drug rash is very complex and can be immunological, as the drug itself can be a complex protein product or a simple low molecular weight chemical, with most belonging to the latter. Low molecular weight chemical drugs are haptens and must first combine with certain macromolecular substances such as proteins to form a hapten-carrier complex, which can then trigger a specific immune response in the body. Immunogenic conjugates are usually formed through covalent bonds, mostly irreversible, and prone to antigenic effects. The type of allergic reaction to drugs can also be type I, or an autoimmune phenomenon. The pathogenesis of drug allergy can also be non-immunological.

Factors affecting drug allergic reactions include: drug dose, the relationship between treatment duration and frequency, method of administration, drug properties, genetic factors, and environmental factors.

[Diagnosis]

1. A clear history of drug use.
2. A certain incubation period, generally 7 to 10 days.
3. Clinical manifestations: sudden onset, often accompanied by systemic symptoms such as fever; polymorphic rash, usually distributed all over the body and symmetrically except for the fixed erythema type; the rash has a bright and consistent color.
4. Skin tests (skin scratch and intradermal tests) sometimes show positive reactions.

bubble_chart Pattern Analysis

1. Wind-heat of External Contraction︰Fever, slight aversion to wind and cold, headache, thirst, generalized erythema or small red papules on the skin, burning sensation, cutaneous pruritus, thin yellow coating, floating and rapid pulse. Commonly seen in scarlet fever-like, measles-like, or urticaria-like erythema. Treatment involves dispersing wind and clearing heat, removing toxins and expelling pathogens. Modified Lonicera and Forsythia Powder: Lonicera, Forsythia 10g each, Bamboo Leaf, Great Burdock Achene, Platycladus 10g each, Reed Rhizome, Imperata Rhizome 30g each, Mentha (to be decocted later), Cicada Slough, Liquorice Root 6g each. For rashes with exudation and yellow greasy coating, add Hypoglaucous Yam, Talc, Akebia Stem 10g each; for severe constipation, add raw Rhubarb Rhizome 10g; for high fever, add Gypsum 30g and Anemarrhena 10g; for cases with only local symptoms and no systemic manifestations, use Mulberry Leaf and Chrysanthemum Decoction with modifications: Mulberry Leaf, Chrysanthemum Flower, Bitter Apricot Seed, Forsythia, Reed Rhizome, Mentha, Cicada Slough, Liquorice Root.
2. Exuberant Heat Toxin︰High fever, thirst, dysphoria, slight constipation, or jaundice, generalized red skin with patches of macules, burning pain, or erosion and crusting. Red tongue with yellow coating, rapid pulse. Commonly seen in exfoliative dermatitis, erythema multiforme, and bullous epidermal necrolysis. Clearing heat and removing toxin, dissipating ecchymosis. Modified Ecchymosis-Dissipating Decoction: Gypsum 50g, Moutan Bark and Red Peony Root 15g each, Unprocessed Rehmannia Root 20g, Buffalo Horn 30g (to be decocted first), Anemarrhena 10g. If accompanied by edema, scanty urine, exudative rashes, blistering, swelling, and a yellow greasy tongue coating, add Coptis Rhizome 6g, Phellodendron Bark 10g, Gardenia Fruit 10g, Talc 15g, Akebia Stem 10g. For severe constipation, add Raw Rhubarb Rhizome 10–20g (to be decocted later). If the yellow coating is gone, fever is worse in the afternoon, or accompanied by bleeding symptoms (e.g., hematuria, bloody stool, purplish-red rashes, restlessness, unconsciousness), use Rhinoceros Horn and Rehmannia Decoction or Plague-Clear Toxin-Vanquishing Decoction with modifications, and administer Peaceful Palace Bovine Bezoar Pill, Purple Snow Bolus, or Supreme Treasured Pill.
3. Pathogenic Heatdamage to Fluid︰Main symptoms: fever or low-grade fever, thirst, flushed face and body, dry mouth and throat, or even epistaxis, gradual subsiding of red and swollen rashes, reduced exudation, or scaling. The tongue is red and dry with little or no coating, and the pulse is thready and rapid. This is commonly seen in the late stage (third stage) of exfoliative dermatitis or bullous epidermal necrolysis-type drug rash. Modified Fluid-Increasing Decoction combined with Stomach-Tonifying Decoction: Scrophularia Root 20g, Unprocessed Rehmannia Root, Dendrobium, Coastal Glehnia Root 15g each, Anemarrhena, Ophiopogon Tuber, Polygonatum Sibiricum, Codonopsis 10g each, Prepared Liquorice Root 6g. Modifications: For severe drug rashes, such as exfoliative dermatitis or bullous epidermal necrolysis and atrophy necrosis types, integrated Chinese and Western medicine treatment is recommended, combining the above pattern identification and treatment with Western desensitization therapy using hormones.