Purpura is a common disease among skin bleeding disorders, and diseases causing subcutaneous bleeding on the skin are collectively called purpura, mostly allergic purpura due to vascular system disorders (Hen-Hsu’s disease), and primary thrombocytopenic purpura due to thrombocytopenia. The causes of purpura bleeding can be grouped into two categories: (1) Vascular system disorders: due to lesions in the blood vessels themselves, such as damage to the vessel walls or increased permeability and fragility of the vessel walls, causing leakage of red blood cells from the vessels to the surrounding tissues and forming purpura. Vascular damage can be caused by bacterial endotoxins/exotoxins, chemical toxins, vitamin CK deficiency, and other factors. Common clinical diseases such as: simple purpura, allergic purpura, intravascular pressure increasing purpura, etc. (2) Hematologic lesions: bleeding caused by blood system coagulation dysfunction. Such as thrombocytopenic purpura, hemophilia, fibrinogen-reducing purpura, prothrombin-reducing purpura due to hepatitis/cirrhosis, purpura caused by excessive application of anticoagulant drugs during the treatment of cardiovascular/cerebrovascular diseases. All of these lesions not only cause bleeding from the skin, but also from other tissues and internal organs. So when you have purpura, you can’t just think it’s bleeding from the skin, you should carefully check all the system organs to exclude the primary hematologic disease. There are also some special types of purpura, such as rheumatic purpura, thrombotic purpura, etc., which need to be examined systematically to find out the cause and the disease. There are many ways to classify purpura, according to the routine blood test can be divided into thrombocytopenic purpura and non-thrombocytopenic purpura; some people are divided into inflammatory purpura and non-inflammatory purpura according to the damage of blood vessel wall. Allergic purpura is the most common purpura in clinic, its clinical typing: (1) simple purpura: generally no systemic symptoms, usually two lower limbs (a few patients can spread to waist, buttocks) can appear scattered pinhead size bright red petechiae, pressure does not fade, part of the rash can fuse into petechiae, no pain or itching, a few days later the color gradually fades and fades. This time the disease is not healed, and there may be new petechiae produced. (2) Renal purpura: It is the most serious type, besides the skin manifestation of simple purpura, there may be facial swelling, lumbar pain, proteinuria, hematuria, tubular type in urine examination at the same time, repeated attacks may cause renal failure. (3) Arthritic purpura: slightly elevated rice-grain size petechiae appear on both lower limbs, also petechiae, petechiae, wind masses or edematous erythema, accompanied by painful swollen joints, intra-articular bleeding, also fever, weakness of limbs and other systemic symptoms, sometimes requiring hospitalization. (4) Abdominal purpura: The skin manifestation is the same as simple purpura, but abdominal pain, vomiting, diarrhea, urgency, blood in stool and other symptoms can appear, and serious cases can be complicated by intussusception. Sometimes the abdominal symptoms appear first and the skin petechiae and petechiae are not obvious, so clinicians need to distinguish carefully to make a correct diagnosis! Common causes of purpura: 1, infection: bacteria (upper respiratory tract infection due to Streptococcus haemolyticus is most common, others are Staphylococcus aureus, pneumococcus, Mycobacterium tuberculosis), viruses (rubella, chickenpox, measles virus, influenza virus, etc.) and intestinal parasites (such as: roundworms). 2, food: fish, shrimp, crab, eggs, dairy and other high-protein foods. 3, drugs: antibiotics, antipyretic and analgesic drugs, etc. 4, other such as cold, vaccination, etc. Treatment: It is recommended that all purpura patients should be treated in regular hospitals to identify the cause and treat it in time. Some physicians are cool to use hormones to treat allergic purpura, but I usually recommend looking for the cause first, especially to exclude factors such as infection, and use drugs such as compound salvia appropriately to minimize the use of hormones!