Patients with varicose veins treated with sclerotherapy may experience a small amount of thrombosis in the varicose veins. If the thrombosis is large, it can lead to hyperpigmentation of the local skin. This is because when the sclerosing agent disrupts the lining of the vessel, the blood in the vessel refluxes into the varicose vein and interacts with the sclerosing agent to form a small amount of thrombus locally. The thrombus can lead to superficial phlebitis and the patient will show localized redness, high skin temperature and skin pigmentation, which can be absorbed slowly over time. Therefore, varicose veins are treated with sclerotherapy, which is very safe and effective. The dosage of sclerosing agent is relatively small, especially the foam sclerosing agent is used now. The effect on the deep veins is very small, and there are very few patients who suffer from deep vein thrombosis after surgery, so it will not bring very troublesome complications to the patients.