Generally speaking, drug eruption occurs after 7 ~ 10 days of sensitization after starting treatment. However, if you have received the same drug or drug treatment with the same structure before, you can appear quickly within a few hours or 1 ~ 2 days. The common skin manifestations of drug eruption are as follows.

1. Eruptive drug eruption

It is the most common drug eruption, accounting for about 95% of all drug eruptions. The clinical manifestations are diffuse bright red spots or red maculopapules about half a grain of rice and beans, which are densely and symmetrically distributed and shaped like measles or scarlet fever. Sudden onset, often accompanied by chills, high fever (39 ~ 40℃), headache, general malaise, etc. More than half of the cases completely disappeared within 2 weeks after drug withdrawal. If the drug is not stopped in time, it may develop into exfoliative dermatitis with poor prognosis.

2. urticaria-like drug eruption

It is one of the common drug eruptions, and its pathogenesis can be type ⅰ and ⅲ allergic reactions. Rash is characterized by the appearance of wind masses of different sizes. This kind of wheal rash is redder than common urticaria, lasting longer, itching consciously, and may be accompanied by tingling and tenderness. Urticaria can appear as the only symptom, or it can be the symptom of serum sickness-like syndrome and anaphylactic shock. Generally, allergic patients appear wheal rash and itching only a few hours after taking the medicine, but a few patients appear dizziness, upset, red wheal, itching, blood pressure drop and other symptoms within a few minutes after injecting penicillin, serum protein and other drugs.

3. Exfoliative dermatitis

Often due to the failure to stop using sensitizing drugs in time and properly handle them, the disease develops, and the rash is combined with exfoliative dermatitis, or it suddenly occurs at the early stage of the disease. Skin lesions are characterized by bright red swelling of the whole body skin, accompanied by exudation and scabbing, followed by large leaf scales falling off, and the exudate smells bad. Mucosa can have congestion, edema, erosion and so on. If this skin lesion is the first onset, the incubation period is generally more than 20 days. At first, it can spread all over the body, or it can occur on the basis of the above measles or scarlet fever-like lesions. The course of disease is more than 1 month, which is a serious drug eruption, often accompanied by systemic symptoms, such as aversion to cold, fever, vomiting and nausea, and some may be accompanied by systemic symptoms such as lymphadenopathy, proteinuria, hepatomegaly and jaundice.

4. Epidermolysis bullosa necrosis type

It is the most serious type of drug eruption, characterized by acute onset. The rash first started on the face, neck and chest, with dark red, dark red and slightly iron gray spots, which quickly merged into blocks and developed throughout the body. Relaxing blisters and epidermolysis of different sizes appear on the spots, which can be wiped off by pressing with your fingers with a little force, such as burns. Mucosa also has a large area of necrosis and shedding. The symptoms of systemic poisoning are serious, accompanied by high fever and visceral lesions. If the rescue is not timely, he may die of infection, toxemia, renal failure, pneumonia or bleeding. Some patients initially showed erythema multiforme or fixed drug eruption, and soon developed into erythema, bulla and exfoliation.

Step 5 fix erythema

The more common types of drug eruption. Special shape, easy to identify. The rash is characterized by localized round or oval erythema, bright red or purple, edema, and blisters can be formed in the center of patients with severe inflammation. The injury boundary is clear, and there are still pigment spots after healing. After each application of sensitizing drugs, it recurs in the same place, and some add new injuries at the same time. The number of rashes can be single or multiple, and some are distributed all over the body. The size of the rash is generally 0.2 cm to several cm. Rash can occur in any part of the body, especially at the junction of skin and mucosa such as lips, mouth, glans penis and anus, as well as the skin between toes, back of hands and back of feet. It occurs at the junction of skin and mucosa, accounting for about 80%, and oral mucosa can also erupt. The regression time of fixed drug eruption is generally 1 ~ 10 days, but patients with mucosal erosion or ulcer often have a long course of disease, which can delay recovery for dozens of days.

6. Erythema multiforme

Erythema multiforme, which can be caused by drugs, presents as round or oval edematous erythema or papules, the size of which is peas and broad beans, with blisters in the center and purple edges. It occurs symmetrically in the limbs and is often accompanied by fever, joint pain and abdominal pain. Severe cases are called Stevens-Johnson syndrome, which can cause mucosal blister erosion pain. The course of disease is usually 2 ~ 4 weeks.

7. Drug allergy syndrome

The specific reaction caused by drugs is manifested as triple symptoms of fever, rash and damage to internal organs (especially liver). It can appear 7 ~ 28 days or longer after the first medication. If you use this medicine again in the future, you can get sick within one day. The initial symptom is fever, which can reach up to 40℃. Followed by edema around the mouth and face, cervical or systemic lymphadenopathy, laryngitis. Skin lesions begin on the face, upper trunk and upper limbs. It is erythema, papule or measles-like rash, which gradually turns dark red. Fusion and gradually develop into erythroderma.

Visceral damage occurs within 1 ~ 2 weeks after eruption, or as long as one month. Hepatitis is the most important symptom. Serum transaminase is increased to varying degrees, and there is generally no jaundice. Those with jaundice usually have a poor prognosis. Fulminant hepatic necrosis and liver failure are the main causes of death. In addition, it may also cause damage to kidneys, lungs, heart and central nervous system.

Abnormal blood system is characterized by atypical lymphocytosis, which occurs in the first 2 weeks. Usually in the second to third week, blood eosinophils increase.

8. eczema type

Often caused by topical drugs, local contact is sensitive. After eczema-like dermatitis occurs, eczema-like lesions can appear all over the body after oral administration or injection of similar drugs. The course of the disease usually lasts more than one month.

9. Photosensitive dermatitis type

The rash is eczema-like, especially in the exposed parts, but it can also occur far away from the exposed parts. After stopping the drug, the reaction can last for several weeks. If you take the medicine again and irradiate the skin with light, it can arouse eczema-like reaction within 48 hours. Spectral toxicity and photosensitivity.

10. lichenoid eruption type

Clinically and pathologically, the lesions are very similar to lichen planus and purplish red papules, with or without oral invasion. Skin lesions are extensive, invading trunk and limbs. Scales are obvious with eczema-like changes, and there is obvious pigmentation after healing. After drug withdrawal, the skin lesions gradually subsided, some of which were chronic and lasted for a long time.

1 1. Purpura type

The main clinical manifestations are hemorrhagic purple spots, needles as big as beans or larger, and flat or slightly raised rashes. This rash may be caused by thrombocytopenia or vascular injury.

12. Vasculitis type

It mainly occurs in small blood vessels, and its inflammation can range from mild cell infiltration to acute necrosis, and in severe cases it can invade blood vessels of many organs, including skin and kidneys. Skin lesions are characterized by purpura, ecchymosis, nodules, necrosis and nodular polyarteritis-like lesions. The general manifestations are fever, joint pain, edema, proteinuria, hematuria or renal failure, and myositis, coronary arteritis, pneumonia and gastrointestinal bleeding rarely occur.

13. Generalized pustular type

Also known as acute generalized exanthematous pustulosis. Rashes often start on the face and wrinkles, and then spread. It is a superficial aseptic pustule without follicles, with a needle tip as large as half a meter, scattered densely and acute. Burning or itching. After stopping the drug for a few days, it subsided and a large area of desquamation appeared. In severe cases, pustules can fuse into pus lakes. May be accompanied by fever, chills, increased white blood cell count, eosinophilia, hypocalcemia, renal failure and other systemic symptoms, occasionally ecchymosis, purpura, erythema multiforme target rash, vasculitis-like rash, blisters, facial edema and mucus erosion.

14. Acne-like rash

It is characterized by follicular papules and pustules, and the damage is similar to acne vulgaris. The development is slow, often occurring more than 1 ~ 2 months after taking the medicine. The course of disease is chronic, and it can be delayed for several months after drug withdrawal.