A 4-year-old baby’s buttocks become red due to intestinal dampness and heat. Pay attention to a light diet, avoid spicy foods, maintain cleanliness around the anus, and observe for symptoms such as diarrhea. Choose cotton underwear, ensure good ventilation, and frequently wash the buttocks with clean water. Dab a sterile cotton swab with iodine tincture, dip it into the iodine tincture bottle once, and disinfect from the inside out three times, applying it three times a day.