fixed drug eruption
Introduction
Introduction to fixed drug rash A drug used for prevention, diagnosis, and treatment, which has an adverse reaction to skin and/or mucous membrane damage after entering the body by any means, has an onset of acute illness, and the lesion is isolated or has a clear circle or ellipse with several clear boundaries. The characteristic of edematous erythema is called fixed erythematous drug eruption. It is a common disease in dermatology emergency department. The fixed drug rash has a special shape and is easier to identify. It is characterized by local itching, followed by round or oval erythema, the color is bright red or purple, edematous, the deeper the pigment, the deeper the pigmentation, and the remaining pigmentation. The obvious difference between this rash and other rashes is that they often occur in the same area after taking the same drug. Generally speaking, a fixed drug rash occurs in the external genitalia, the lips and the back of the hand. This drug rash has a certain incubation period, usually occurs within 4 to 20 days after the first administration. If the drug is repeatedly administered, the body is in a sensitized state, it will occur within 24 hours, while the sensitive person will be in a few minutes or hours. Can happen. basic knowledge The proportion of sickness: 0.01% Susceptible people: no specific population Mode of infection: non-infectious Complications: edema
Cause
Fixed drug eruption
Drug factors (78%):
Drugs causing fixed drug eruptions, according to relevant research statistics, are mainly sulfonamides, such as long-acting sulfonamides, sulfaguanidines, SMZ, etc., followed by antipyretic analgesics, such as analgin, aspirin, quick-acting cold capsules, etc.; There are sedatives for sleeping in peace, such as luminal, quick sleep, etc., and more common in barbiturates. Some compound drugs contain the above-mentioned sulfa drugs, antipyretic analgesics, sleeping sedatives and other pharmaceutical ingredients, and this type of drug rash can also occur. For example, some compound cold medicines often contain aspirin to induce this disease.
Prevention
Fixed drug rash prevention
1. According to the general routine care of dermatology;
2. Give high protein, high vitamin fluid or semi-liquid diet;
3. Strengthen the care of facial features and mucous membranes to prevent complications;
4. Significant signs should be given to sensitizing drugs to prevent recurrence of allergies;
5, keep the clothes and clothes clean, dry and smooth;
6, strict aseptic operation, the bullous lesions can be puncture drainage in the low position or use the empty needle to suck out the blister fluid, pay attention to protect the wound surface, the infected epidermis should be removed;
7. Before using the medicine, inquire about the history of allergies in detail to prevent cross-allergic reactions. For penicillin, sulfonamides, novocaine, antipyretic and analgesic, sedatives, antibiotics, etc., scratches should be strictly followed in accordance with the operating procedures before use. Or intradermal test;
8. Encourage more drinking water and promote drug discharge.
Complication
Fixed drug eruption Complications edema
Can be secondary to infection.
Symptom
Symptoms of fixed drug eruptions Common symptoms Blisters or bullae damage secondary infections of round or oval erythema
A fixed erythema type drug eruption or fixed drug eruption is a light drug eruption, which is more common.
1. Initiation of drugs: often sulfonamides, antipyretic and analgesic, hypnotic and sedative, tetracycline, phenolphthalein and so on.
2. Clinical manifestations: acute onset, skin lesions are isolated or several clear circles or oval edematous erythema, generally asymmetrical, 1 ~ 4cm in diameter, heavy erythema can appear bullae, itching and general No systemic symptoms, skin lesions can occur in any part of the skin, located in the lip, mouth, glans, anus and other skin and mucous membrane junctions, often prone to erosion or secondary infection and cause pain, at this time, patients often come to the emergency department, The skin lesions did not retreat for 1 week, leaving gray-black pigmentation spots. After taking the medicine for a long time, it was itchy in a few minutes or hours, and then the same damage occurred and expanded to the surrounding area, resulting in The central pigment is deepened and the edge is flushed. When recurring, new lesions may appear in other areas.
Examine
Fixed drug eruption examination
The disease usually has a clear history of medication, and may cause allergic reactions directly due to certain components in the drug. Therefore, the following clinical examination items are mainly carried out:
1. Blood routine: Because the disease is related to allergic factors, the number and proportion of eosinophils may be significantly increased, and the number of neutrophils and monocytes is relatively reduced.
2. Allergen detection: Because the disease is related to allergic factors, the body is usually an allergic constitution, so the allergen test can determine whether there are other allergic substances.
3. Biochemical items: Severe cases can cause liver and kidney function damage and electrolyte imbalance, and even liver and kidney failure, and biochemical items should be reviewed during clinical treatment.
Diagnosis
Diagnosis and identification of fixed drug eruptions
diagnosis
Diagnosis can be based on medical history, clinical symptoms, and laboratory tests.
Differential diagnosis
The diseases that need to be differentially diagnosed with fixed drug eruptions are:
(1) foreskin balanitis: often occurs in a certain degree of foreskin is too long, can be caused by a variety of different reasons, such as smegma and local physical factors, various infectious factors, such as foreskin and glans redness, erosion, The patient has no history of drug allergy;
(2) hard sputum: for the first-stage syphilis damage, manifested as erosive papules of the external genital tract, with serous exudation, the surface is flat and clean, the edge is slightly higher, the number is one or two, no pain, easy to self-heal The syphilis spirochete was positive.
