Influence of genetic factors (allergic constitution), certain enzyme defects, and pathological/physiological conditions of the body

Antibiotics: penicillins, cephalosporins, tetracyclines, aminoglycosides

Sulfonamides: Sulfamethoxazole

Antipyretic and analgesic: salicylic acid preparations

Anti-epileptic and sedative drugs: phenytoin, barbiturates, Chinese herbal medicines

Others: allopurinol, isoniazid, furazolidone, hydralazine, allogeneic serum preparations/vaccines, biological agents

type

Features:

Photoallergic drug eruption: an allergic drug eruption caused by a small number of drugs entering the human body and converting into antigenic substances under the induction of light

Pharmacological effects: For example, aspirin can directly induce mast cell degranulation and release histamine, causing urticaria. Drug interactions

Adverse drug reactions and dysbiosis

Overdose reaction and accumulation effects: such as liver and kidney insufficiency, slow drug excretion, and prolonged use of drugs

Defect/inhibition of enzymes involved in drug metabolism: e.g. phenytoin hypersensitivity syndrome (cyclooxygenase hydrolase deficiency) Drug exacerbating an existing skin disease

Fixed (fixed) drug eruption: more common, often occurs at the junction of skin and mucous membranes (such as around the mouth and nose, external genitalia and perianal area). Each occurrence is often in the same location. It is common in antipyretic analgesics, sulfonamides, and antibiotics. Biturates and tetracyclines; manifested as localized round/oval edematous purple-red/bright red macules/patches with clear boundaries that subside after 1 to 10 days, leaving pigmentation; there is itching/pain, but the symptoms are normal No systemic symptoms

Urticarial drug eruption: more common, especially serum products, furazolidone, penicillin, and aspirin; manifests as generalized wheals, flushing and edema all over the body, and slow subsidence; angioedema may occur, accompanied by stinging and tenderness; also Serum sickness-like symptoms (fever, joint pain, lymphadenopathy, proteinuria) may occur; in severe cases, anaphylactic shock may occur

Exanthematous drug eruption/measles type or scarlet fever type drug eruption: the most common (90%); common in semi-synthetic penicillins, sulfonamides, antipyretic analgesics, barbiturates; often a few days after the first dose (not more than 2w) ) occurs; it manifests as measles-type/scarlet fever-type erythema/papule herpes fused into large areas, often symmetrically distributed on the trunk and limbs (the face is rarely involved), accompanied by fever, itching, and eosinophils↑; half of the disease course is 1 to 2 weeks , may be accompanied by bran-like desquamation after the skin lesions subside.

Drug-induced bullosa epidermolysis/drug-induced toxic epidermal necrolysis (TEN): the most serious, common in sulfonamides, antipyretic analgesics, antibiotics, and barbitol steroids, carbamazepine, allopurinol, and anti-tuberculosis drugs; the onset is sudden, manifested as diffuse erythema over the body, blisters of varying sizes quickly appearing, the blister walls are loose, Nissl's sign is positive, and large erosions form when rubbed. With exudation; skin tenderness is obvious; the mucous membranes of the eyes, mouth, nose, genitals, and anus are often involved, manifesting as congestive inflammation, erosion, and exudation, causing corresponding symptoms (such as photophobia, blurred vision, and oral pain that affects eating) ; Systemic poisoning symptoms are severe, and there may be significant internal organ damage

Exfoliative dermatitis type drug eruption (drug-induced exfoliative dermatitis): It is severe and is common in sulfonamides, barbiturates, anti-epileptic drugs, antipyretic analgesics, and antibiotics. It mostly occurs after long-term use of drugs; the incubation period of the onset is long ( More than 20 days), the condition worsens progressively; it starts out as measles-like/scarlet fever-like skin lesions, gradually worsens and merges into diffuse flushing and swelling all over the body (especially the face, hands and feet), accompanied by blisters, erosion, exudation, and scabs, which may There is a special odor; after 2 to 3 weeks, the redness and swelling gradually subside, and a large amount of scaly/leaf-like desquamation appears all over the body. The palms and toes peel off like gloves/socks, and the hair and fingernails may fall off; the oral mucosa and eye conjunctiva may be involved. ; Systemic symptoms are obvious

Eczema-type (eczematous) drug eruption: It is more common in local contact dermatitis caused by external use of penicillin and sulfa drugs, and then oral/injection of similar drugs, resulting in generalized eczema-like changes throughout the body.

Acneiform drug eruption: common in long-term use of halogen preparations, glucocorticoids, and birth control pills; manifests as follicular papules and papulopustules on the face/chest and back; the course of the disease is slow, and generally there are no systemic symptoms

Purpuric drug eruption: common in antibiotics, barbiturates, and diuretics; often occurs in both lower limbs, symmetrical on both sides, manifesting as needle-to-pea-sized petechiae/ecchymoses, scattered/densely distributed, slightly raised, and compressed It does not fade. In severe cases, it may be accompanied by joint swelling and pain, abdominal pain, hematuria, and blood in the stool.

Erythema multiforme drug eruption: common in sulfonamides, antipyretic analgesics, and barbiturates; divided into mild and severe types, with symptoms basically similar to erythema multiforme

photosensitive drug eruption

Drug hypersensitivity syndrome (DHS)/drug eruption with eosinophilia and systemic symptoms: usually occurs within 2 to 6 weeks after the first dose, and may occur within 1 day after re-administration. It is more common in epoxides Individuals with hydrolase deficiency; the inducing drugs are mainly anti-epileptic drugs and sulfonamides; manifested as skin lesions and visceral damage (such as lymphadenopathy, hepatitis, interstitial nephritis, interstitial pneumonia, myocarditis, fulminant liver damage is the main cause of death) Hematological abnormalities (eosinophils ≥1000/L, positive atypical lymphocytes)

Others: chloasma-like, skin pigmentation, SLE-like, lichen planus-like, pemphigus-like, pustular

Skin test, drug provocation test (only applicable to those with mild drug rash caused by oral drugs and the disease itself requires the use of the drug for treatment)

Higher security

① Disable allergenic drugs;

②Accelerate the excretion of drugs (drink more water, intravenous infusion);

③Give anti-allergic and anti-inflammatory treatment, supportive treatment, and prevent secondary infection;

④Give different treatments according to the severity of the condition (see below for details)

Mild: When the rash and systemic symptoms are mild, only symptomatic treatment can be given

Severe: Need to be hospitalized for rescue

anaphylactic shock