In 2011, I wrote “Talking about pediatric allergic purpura” because of the fear and confusion of many parents about this disease. Recently, many parents are distressed by the small amount of rash on their children’s legs and even turn to seek medical help. As mentioned before, allergic purpura usually has four major symptoms: rash, joint pain in the lower extremities, abdominal pain and kidney damage (manifested as hematuria and/or proteinuria when examined in the urine). The rash of allergic purpura usually appears as bleeding dots of varying sizes on the extensor side of the lower extremities (also known as the front), small ones like the size of a pinpoint, large ones like millet, mung beans, or adzuki beans, one by one, bright red at first, darkening after a day or two, and finally dissipating into a bruise. Some children’s rashes are fused into flakes of different sizes, which looks very worrying and frightening. In fact, the rash is the least important symptom in the disease of allergic purpura, no matter how much or how big the rash is and how worrying it looks at first, it will gradually darken and fade and will not leave scars and pigmentation in the future. We usually remember to look at the lower extremities because of the pain in the child’s legs and feet, and it is only because we see this typical rash that we confirm the diagnosis of allergic purpura. A few children have joint swelling and pain or abdominal pain before the rash appears, and we have no way to know the exact cause, and only when the rash appears does it dawn on us that it is allergic purpura. As a result, children with post-rash allergic purpura are often not diagnosed in time, and suffer even more from abdominal pain for which no cause can be found. In this sense, the rash is also a great contribution to the timely and clear diagnosis.