The etiology of superficial phlebitis of the lower extremities includes chemical irritation, catheterized persistent infusion, varicose veins of the lower extremities, and other factors, and its clinical manifestations include pain, redness, and swelling of the stripes. 1.Etiology: (1) Chemical stimulation: Intravenous injection of various irritating solutions or hypertonic solutions, such as intravenous injection of hypertonic solutions, sclerosing agents, various antibiotics, etc. can cause chemical stimulation on the endothelium of the injected superficial vein, followed by obvious inflammatory reaction. (2) Continuous infusion of catheterized fluids: this can be seen in patients with serious illnesses such as major surgery and extensive burns, which damages the vein wall and results in an inflammatory reaction. (3) Varicose veins of the lower limbs: in varicose veins of the lower limbs, blood stagnates in the veins, chronic infection occurs in the skin due to nutritional reasons, and the varicose veins suffer from hypoxia and inflammatory damage, leading to superficial phlebitis. (4) Other factors: it is related to factors such as increased blood coagulability, and it is also related to diseases such as cancer and lymphoma. 2. Clinical manifestations: the typical symptoms are localized red and swollen strips in the form of reticular and columnar suddenly, elevated skin temperature, obvious pain and tenderness. Patients with superficial phlebitis of the lower limbs should go to the hospital in time and receive standardized treatment under the guidance of doctors.