Black toes may be caused by physiological factors such as discoloration of shoes and socks, or it may be caused by trauma, nail fungus disease, diabetic foot and other factors. 1. Physiological factors: If shoes and socks are black and there is color loss, the toes may be blackened. 2. Trauma: If the foot is hit, it may lead to the formation of subcutaneous blood in the toe area, making the toe black and may be accompanied by painful symptoms. 3. Nail fungal disease: fungal infection of toenail nail plate and subnail tissue, causing thickening of the nail plate, gray and yellow turbidity under the nail, black performance. 4. Diabetic foot: diabetic foot is mainly caused by diabetic peripheral neuropathy, diabetic vasculopathy and other factors, triggering factors include infection, smoking, etc., which will lead to insufficient oxygen and blood supply to the foot, skin necrosis, resulting in the phenomenon of black toes. After ruling out physiological factors, patients are advised to be admitted to the hospital for examination to find out the exact cause of the blackened toes.