The most common clinical manifestations of allergic purpura are bleeding spots on the lower limbs, hematuria, melena, and joint pain. The presence of melena or bloody stools accompanied by abdominal pain often indicates bleeding from the intestinal mucosa. It is recommended to complete a mesenteric vascular color Doppler ultrasound as soon as possible to identify the bleeding sites. At this time, fasting is absolutely necessary, meaning no food or water should be consumed, as this can exacerbate abdominal pain and bleeding. Fasting should continue until the melena and pain are alleviated. If symptoms continue to worsen, surgery may be necessary to prevent intestinal perforation and the onset of acute peritonitis.