Hello, yes, blackening is due to the long-term lack of nutrition in local limb muscles, so the color will turn black. The swelling and blackening of the skin of the lower limbs indicate that varicose veins are in the middle stage. If you don't intervene at this stage, it will easily lead to lower limb ulcers. At that time, the cost and difficulty of treatment will increase, and the long-term unhealed ulcer will also increase the psychological burden of patients. It is suggested that this kind of medicine should go to a regular specialized hospital to check the blood vessels of lower limbs in time, and find out the condition and treat it actively under the guidance of a doctor.