Anaphylactic purpura is a form of vasculitis. Typical signs and symptoms of the disease include purpura, arthralgia/arthritis, gastrointestinal involvement and glomerulonephritis. 1. Skin purpura: palpable purpura, purpuric rash mainly appears on the lower part of the body, such as the extensor surfaces of the lower limbs, waist and buttocks, etc. Petechiae, ecchymoses and hemorrhagic macules are also seen. The color of the lesions will change from red to purple to brown before fading. 2. Joint involvement: 60%~80% of the patients will have joint pain and arthritis, which is usually unilateral and characterized by swelling and pain around the joints and limitation of movement, which is non-migratory and transient, and will not leave any after-effects after subsiding. 3. Gastrointestinal involvement: The main manifestations include abdominal cramps, vomiting, and gastrointestinal bleeding, which usually occurs within a week of the appearance of the rash. The pain is usually periumbilical or epigastric and is worse after meals. 4. Kidney involvement: clinical manifestations range from the more common transient simple microscopic hematuria and mild proteinuria to the less common nephrotic syndrome, nephritic syndrome, acute glomerulonephritis, and even renal failure. If you are not feeling well and have purpura on both lower limbs, it is recommended that you go to the hospital in time and seek treatment under the guidance of a physician so as not to delay your condition.