Causes of old rotting foot ulcers include diabetes, thromboembolic vasculitis, and tinea pedis, and there is no such thing as the fastest solution. The treatment needs to deal with the cause and symptoms, including medication and surgery. 1. Diabetes mellitus: In diabetic foot, ischemic necrosis of the foot is triggered by vascular lesions. At this time, we should actively treat the primary disease and give insulin and other hypoglycemic treatment. If there is a combined infection, control the infection. 2. Thromboembolic vasculitis: Most patients with thromboembolic vasculitis have a history of smoking for many years. On the one hand, it can be given to dilate blood vessels with drugs such as nicardipine and peldipine. In addition, patients should quit smoking. 3. Tinea pedis: for foot ulcers caused by fungal infections, at this time you can give clotrimazole, econazole and other drugs for antifungal treatment, if necessary, oral antifungal drugs for systemic treatment. Combined bacterial infection should be combined with anti-bacterial treatment. The old rotten foot ulcers may be other reasons, it is recommended that the patient timely medical treatment by a professional doctor for standardized diagnosis and treatment.