If one day you suddenly find yourself or your children’s legs appear purple dots, not painful and more and more, do not feel very scary, do not panic, this may be allergic purpura, then this allergic purpura in the end what is going on? How scary is it? The actual allergic purpura is a very good idea. How to treat it? Allergic purpura, also known as Henoch-Schonlein purpura, is a kind of allergic vasculitis that invades the skin and other organs of fine arteries and capillaries, often accompanied by abdominal pain, arthralgia and kidney damage, but the platelets are not reduced. It is thought that allergic purpura belongs to the same spectrum of disease as allergic cutaneous vasculitis. The etiology may be related to streptococcal infections, viral infections, drugs, food, insect bites, etc. The mechanism of occurrence is due to the combination of antigen and antibody to form immune complexes deposited in the vascular wall, which activates complement and leads to inflammation in and around the capillary and small vessel walls, resulting in increased permeability of the vessel walls, resulting in various clinical manifestations. Clinical manifestations Prevalent in children and adolescents, the disease may start with fever, headache, arthralgia, and general malaise. The skin lesions may appear as pinhead to soybean-sized petechiae, bruises or urticaria-like rash, and in severe cases, blisters, hemorrhages or even ulcers may occur. The skin lesions are usually found on the extremities, especially on the lower extremities and buttocks. The lesions are symmetrically distributed, appear in batches, and are prone to recurrence. If there is only skin damage, it is called simple purpura; if there is abdominal pain, diarrhea, blood in stool, or even gastrointestinal bleeding, it is called gastrointestinal purpura; if there is joint swelling, pain, or even joint effusion, it is called joint purpura; if there is hematuria, proteinuria, or kidney damage, it is called renal purpura. Diagnosis Double lower limbs purpura, with abdominal pain, arthralgia or kidney damage, the diagnosis is not difficult. However, when the systemic symptoms appear before the skin purpura, it is easy to misdiagnose as rheumatoid arthritis or acute abdomen, and it needs to be clinically differentiated from these diseases and other types of purpura and vasculitis.