Drug eruption

Introduction to drug rash Drug eruption, also known as drug dermatitis, is a reaction of skin mucosal inflammation caused by drugs entering the human body through oral, topical and injection. Almost all drugs may cause dermatitis, but the most common are iodine, antipyretic and analgesics, sleeping pills, and penicillin and streptomycin. The adverse reactions caused by drugs are very complicated and can be roughly divided into: drug overdose, intolerance, idiopathic, side effects, secondary effects and allergic reactions. Drug eruptions are the most common type of allergic reaction. basic knowledge The proportion of illness: 0.02--0.05% Susceptible people: no special people Mode of infection: non-infectious Complications: anaphylactic shock

Drug eruption cause

Non-antibiotics allergies (25%):

Most drugs have the potential to cause drug eruptions, including Chinese herbal medicines, but most of them are caused by more antigenicity. Commonly used are antibiotics, sulfonamides, aminopyrine, analgin, phenylpredyl, salicylic acid and other antipyretic and analgesic, hypnotic, anti-epileptic, anti-toxin and other serum drugs. According to the analysis of drug structure, all drugs with benzene ring and pyrimidine ring have strong sensitizing power. In addition, for patients with congenital allergic diseases and patients with diseases of vital organs, the risk of drug eruption is relatively high.

Antibiotic allergy (35%):

The form of drug eruption is diverse, and the same type of drug eruption can be caused by completely different drugs. The measles-like erythema types reported in this paper are caused by nearly 10 types of drugs such as penicillins, cephalosporins, and antipyretic analgesics. On the other hand, the same drug can cause several different forms of rash. For example, penicillins, antipyretic and analgesic, cephalosporins, and sulfonamides reported in this group can cause more than three types of rashes. It also brings certain difficulties to the diagnosis, and should be carefully identified to determine the sensitizer.

Pathogenesis

Non-allergic reaction mechanism

Including drug overdose, side effects, direct toxicity, specific response (idiosyeracy), Jarish-Hexheimer reaction, ecologic imbalance, bio-trophic effect, interaction between drugs, etc. .

Allergic reaction mechanism

Most drug eruptions are caused by this mechanism and the mechanism is complicated. Macromolecular drugs such as serum, vaccines, organ extracts, protein products such as enzymes, etc., are themselves whole antigens and have sensitization effects; however, most drugs themselves or their metabolites are small molecules with a molecular weight of less than 1000, half The antigen, when entering the body and irreversibly covalently bond with a macromolecular carrier such as a protein or a polypeptide, has a sensitizing effect after forming a binding antigen. When the body is sensitized by a drug-like antigen and then exposed to the same type of antigen, the body can pass the antibody-mediated allergic reaction of type I, II, and III, or the type IV reaction of sensitized lymphocytes, or both types of reactions. A drug rash occurs when an acute inflammatory reaction occurs in the skin or (and) mucous membranes. Due to the differences in the chemical structure of drugs and the complexity of metabolites, drug antigenic determinants are numerous and complex. In addition, there are differences in the forms of response between drugs to individuals. Therefore, the same drug can be used in different patients. Causes different types of skin damage. Conversely, the same type of skin damage can also be caused by different drugs.

Drug eruptions caused by allergic reaction mechanisms often have the following characteristics:

1 There is no linear relationship between the occurrence of rash and the dose, and it only appears among a few people.

2 After the first contact with the drug, there is a 4 to 20 day incubation period, usually 7 to 10 days. When the drug is contacted later, there is no longer an incubation period, and the disease occurs within a few minutes to 24 hours.

3 clinical manifestations have nothing to do with the pharmacological properties of the drug, sometimes accompanied by asthma, arthritis, lymphadenopathy, peripheral blood citrate granulocytosis, and even anaphylactic shock and other allergic reactions.

4 Cross-reactivity can occur between drugs with structural similarities.

Drug rash prevention

Drug eruptions are iatrogenic diseases, so you must pay attention to:

1. Before the medication, ask the patient what kind of allergy history, avoid using known allergic or structurally similar drugs.

2. The medication should be targeted, try to use less sensitizing drugs. During treatment, you should pay attention to the early symptoms of drug eruption, such as sudden itching, erythema, fever, etc., should immediately stop suspicious drugs, closely observe and strive to determine the sensitizing drugs.

3. When applying penicillin, serum, procaine and other drugs, skin test should be carried out according to the prescribed method. Those who are positive should not be treated with this drug. Before the skin test, emergency medicine should be available for emergency needs. At present, the concentration of skin test solution is penicillin 500u/ml, streptomycin 5mg/m1, procaine 0.25%, and tetanus antitoxin 1:10. The dosage is 0.1m1.

4. If the drug has been diagnosed as a drug eruption, the sensitizing drug should be recorded in the medical record and the patient should be kept in mind. Tell the doctor not to use the drug every time you see a doctor.

Drug eruption Complications anaphylactic shock

A secondary infection will occur. Drug eruptions caused by antiepileptic drugs such as phenytomo and Zhenjinging are often accompanied by fever, swollen lymph nodes, leukocytosis, and liver dysfunction, called drug-induced allergic syndrome.

In short, the dangerous drug rash has three major characteristics:

1, the formation of blisters, and visible skin erosion.

2, accompanied by oral mucosa, eye conjunctiva and other mucosal parts of the rash.

3, can occur fever, lymphadenopathy, leukocytosis and liver dysfunction.

Symptoms of drug eruption Common symptoms Pella-like skin rash, skin, skin, freckle, skin, cyanosis, scarlet fever, rash, erythema (clear boundary)

Measles-like or scarlet-like erythematous drug eruption

Also known as rash type drug eruption. More common, it is a light drug rash, which may be caused by type IV allergy.

1, the triggering drugs are mostly antipyretic and analgesic drugs, barbital, penicillin, streptomycin, sulfonamide and so on.

2, clinical manifestations of sudden rash, often accompanied by mild or moderate fever, moderate or severe itching. Measles-like erythematous drug rash The skin damage is similar to that of measles. It is a scattered or dense red cap-like rash, with a trunk and more general body. Scarlet fever-like drug eruptions are similar to scarlet fever. From the beginning, it is a small erythema, which develops downward from the face, neck, upper limbs and trunk. It can be spread throughout the body in 2 to 3 days. Swelling may occur in the limbs of the face, and the wrinkles and the flexors of the limbs are obvious.

3, differential diagnosis should be differentiated from measles and scarlet fever. According to the drug-free fever and rash, there is no infectious disease rule, no tonsillitis purulent inflammation, Yangberry tongue, catarrhal symptoms and systemic severe poisoning symptoms are identified.

Fixed erythema drug eruption

Or fixed drug eruption, a light drug eruption, more common.

1. The triggering drugs are often sulfonamides, antipyretic and analgesic, hypnotic and sedative, tetracycline, phenolphthalein and the like.

2. The clinical manifestations are acute, and the lesions are isolated or several round or oval edematous erythema with clear boundaries. They are generally asymmetrical, with a diameter of 1 to 4 cm, and bullae may appear on severe erythema. Itchy and generally no systemic symptoms. Skin lesions can occur anywhere on 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, and did not retreat for a long time. When the drug is taken again, itching occurs in the same place in a few minutes or hours, and then the same damage occurs and expands to the periphery, resulting in damage of the central pigmentation and edge flushing. When recurring, new lesions may appear in other areas.

Urticaria drug eruption

More common. Mostly caused by Type I and Type III, and even by Type II allergy.

1, the triggering drugs are mostly penicillin, serum products, , salicylate, sulfonamide, procaine and so on.

2. The clinical manifestations are similar to those of acute urticaria. Can also have high fever, joint pain, lymphadenopathy, angioedema, proteinuria and other serum-like syndrome-like manifestations, and can involve the internal organs, and even anaphylactic shock.

Stevens-Johson syndrome drug eruption

Mostly caused by type III allergy, is a heavy drug rash.

1, the initiation of drugs are often sulfonamides, especially long-acting sulfonamides, barbital, Baotaisong and other antipyretic prodrugs, phenytoin and so on.

2, clinical manifestations of acute onset, accompanied by high fever and other systemic symptoms. Lesions are widely distributed, mainly blistering, bullae, erosion and scarring. Often located around the mouth and severely invade the mucosa. There may be complication of liver and kidney dysfunction accompanied by pneumonia, and the mortality rate is 5% to 10%.

Purpura drug eruption

Caused by type II or type III allergy.

1, the trigger drugs are mostly sulfonamides, phenylbutazone, indomethacin, phenytoin, barbital and so on.

2, the clinical manifestations of light double legs appear sputum or ecchymosis, scattered or dense, severe limbs, trunk can be involved, even accompanied by mucosal bleeding, anemia and so on. The type III reaction is caused by vasculitis. The lesions can be formed from various components such as wheal, papules, nodules, blisters and necrotic ulcers, but all have palpable purpura. In severe cases, there may be kidney, digestive tract, and nervous system involvement, accompanied by systemic symptoms such as fever and joint pain.

Toxic necrotizing epidermolysis drug eruption (TEN)

For the most severe drug eruption, it is generally seen in the emergency department.

1, the initiation of drugs such as sulfonamides, salicylates, phenylbutazone, aminopyrine and other antipyretic analgesics, phenolphthalein, penicillin, tetracycline, barbital, phenytoin and so on.

2, clinical manifestations of acute onset, accompanied by high fever, irritability, lethargy, convulsions, coma and other obvious symptoms of systemic poisoning. The skin manifests as full-thickness of the epidermis and formation of subepidermal bullae. At the beginning, it was a large piece of bright red patches, followed by purple-brown. In 1 to 2 days, bullae appeared on the spots and expanded, and the sub-synthesis was several tens of centimeters in size, showing most parallel strip wrinkles. The bullae are easily rubbed and there is a large smash, similar to a second degree burn.

Nilolsky sign

At the same time, mucous membranes at the mouth, eyes, nose, upper respiratory tract, genitals, and esophagus can be widely affected. A large erosion surface appears after the mucosa falls off. The pain is extreme. The body temperature often lasts at 40 ° C, and does not retreat for 2 to 3 weeks. Heart, kidney, liver, and brain are also often affected. The prognosis is serious, and the mortality rate is 25% to 50%. More often due to secondary infection, liver and kidney dysfunction, water and electrolyte disorders and death.

3. Differential diagnosis needs to be differentiated from toxic shock syudrome. The latter occurs in women with menstrual cramps, although the skin has extensive erythema and desquamation, but no bullae appear, no pain and can be identified. In addition, it must be differentiated from staphylococcal scalded skin syndrome (SSSS). The systemic toxic reaction is also obvious, systemic erythema and bullous lesions appear, but the lesions are shallow, epidermis The fissure formed by the release is in the upper part of the granular layer and the spinous cell layer below the horn layer; while the former occurs below the basal cells. If the diagnosis is difficult, the blister epidermis can be taken for frozen section and HE staining can be used for identification.

Exfoliative dermatitis drug eruption

May be caused by type IV allergy or direct toxicity of heavy metal drugs, is a heavy drug rash.

1, the triggering drugs are mostly luminal, sulfonamides, phenylbutazone, phenytoin, p-aminobenzoic acid, streptomycin, gold, arsenic and other heavy metals. Others such as hydroxypyrazol (Allopurinol), methoxythiophene cephalosporin (Cefoxitin), cimetidine, chloroquine, isoniazid, sulfurylurea (Sulfonylurea) and the like can also be caused.

2, clinical performance for the first time the drug incubation period is long, generally more than 20 days. Some of these patients occurred on the basis of rash-type drug eruptions.

This type of drug eruption has systemic symptoms such as chills and high fever at the onset of the disease. At first, the skin lesions showed measles-like or scarlet-like heat-like damage, and gradually gained weight. Finally, the skin of the whole body showed diffuse flushing and swelling, and blistering, erosion, exudation and scarring appeared in the wrinkles. Itching is heavy; at the same time, lips, oral mucosa flushing, edema or blister erosion, scarring; eye-bound membrane edema, secretions, photophobia. The superficial lymph nodes of the whole body can be swollen. Generally, after two weeks, the redness and swelling are alleviated, the whole body skin begins to scale-like desquamation, the hands and feet can be stripped, and the hair and nails can also fall off. The course of disease is 2 to 4 weeks. Severe cases may be associated with bronchial pneumonia, toxic hepatitis, nephritis, skin infections, and even sepsis. If not handled properly, it can be life-threatening with water and electrolyte disturbances and secondary infections.

Light-sensitive drug eruption

Skin lesions occur after UV exposure. There are two types of phototoxicity and photoallergic reactions.

1. Induced drugs such as sulfonamides, tetracycline, griseofulvin, phenothiazines, nalidixic acid, diphenhydramine, desminol, quinine, isoniazid, vitamin B1, methotrexate, etc.

2, clinical manifestations of phototoxic reaction damage, can occur in the first dose of patients, 2 ~ 8h after sun exposure, erythema, edema or bullae in the skin of the exposed area. Photoallergic responsive lesions have a sensitization latency of 5 to 20 days after exposure, and then occur within a few minutes to 48 hours after exposure. Lesions can be erythematous lesions, or polymorphic lesions such as papules, edematous plaques, nodules, blisters or eczema. In addition to exposure, non-exposed areas can also occur. All with itching.

Systemic lupus erythematosus (SLE) syndrome-like response

1. A drug that induces SLE refers to a drug that stimulates a potential SLE or aggravates the symptoms of SLE that have occurred. Mainly penicillin, sulfonamides, phenylbutazone and so on. The clinical manifestations are the same as SLE. After stopping the drug, it does not stop the development of the disease.

2. A drug that produces SLE refers to a drug that has the efficacy of causing SLE syndrome. Mainly hydralazine, procainamide, isoniazid, phenytoin and the like. The clinical symptoms caused are the same as true SLE, but lighter. Anti-nuclear antibody titers are high, lupus erythematosus cells (10), while anti-double-stranded DNA antibodies (-), total complement activity values are normal. The kidney and central nervous system are rarely affected. It can be cured after stopping the drug.

Drug eruption check

Routine inspection:

1. Blood routine examination: including red blood cells, white blood cells, hemoglobin and the number of platelets. The blood routinely collects the finger blood or the peripheral blood of the earlobe by acupuncture. After dilution, it is dropped into a special calculation disk, and then the number of blood cells is calculated under a microscope.

2. Urine routine: including urine color, transparency, pH, red blood cells, white blood cells, epithelial cells, casts, protein, specific gravity and urine sugar qualitative.

3. Biochemicals: The content of various ions, sugars, lipids, proteins and various enzymes, hormones and various metabolites of the body present in the blood.

Drug eruption diagnosis

Because of the clinical type of drug eruption, emergency engineers should always be alert to the possibility of drug eruption, but must be able to rule out the disease they have simulated before making a correct diagnosis. Because the drug eruptions seen in the emergency department are mostly allergic reactions, the following rules are helpful for diagnosis:

1 has a clear history of taking medicine;

2 There is a certain incubation period for initial contact;

3 The rash occurs suddenly, most of them are symmetric distribution, and the progress is fast. It can be spread all over the body in 1-2 days. The rash is bright red with itching. There is no infection between the rash and fever;

4 For complex cases of multiple drugs, the time is mainly based on the relationship between the drug and the rash, and the rash type and the induced drug are analyzed to find the sensitizing drugs. For the first-time use of drugs, the analysis focus is generally limited to two weeks; for re-users, it can be limited to three days.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.