If the buttocks of an elderly person is rotten, it is more likely to be a skin ulcer, which mostly occurs in bed-ridden elderly people, due to poor skin supply function caused by poor local blood circulation, resulting in skin ulceration. In clinical treatment, a 2% boric acid solution can be applied wet, and if there is purulent exudate and pus crust, a solution of Revnur can be applied wet, twice a day for twenty minutes. After the wet dressing, apply fusidic acid ointment or compound polymyxin B ointment twice a day to prevent infection and antibacterial and anti-inflammatory effects. If there are more pustules and crusts, you need to clear the wound and then take oral roxithromycin capsules or amoxicillin capsules for treatment. If it is dry, you can apply topical Bevacin to promote the growth of local epidermis.