The common causes include sebaceous cysts, boils, etc. They need to be treated according to the cause, and are usually removed by medication and surgery. 1. Sebaceous cysts: Sebaceous cysts are easily induced when the sebaceous ducts in the skin at the base of the thighs are blocked, manifesting themselves as round, medium-hard or elastic cysts on the surface of the skin, and redness, swelling, pus, and pain will occur when a bacterial infection is secondary. Erythromycin ointment and mupirocin ointment can be applied locally. After the inflammation subsides, surgical excision can be used for treatment. 2. Boils: When there is a wound on the skin at the root of thigh, bacteria will invade from the mouth of hair follicles and boils will occur, which will be manifested as single or multiple red, hemispherical and painful hard packs in the hair follicles and deep tissues around the hair follicles. In the early stage without pus, local topical ichthyol ointment, mupirocin ointment, etc., the more serious symptoms can be combined with the application of oral drugs, such as amoxicillin capsules, cefaclor granules, etc., the appearance of pus, rupture of the symptom, the doctor will be removed by surgical incision of the lesion, the drainage of pus. There may be other causes for the growth of a large hard bag on the inner thigh root, it is recommended to go to the hospital in time to improve the examination, to clarify the cause of the disease and then give targeted treatment. All of the above medications should be used under the guidance of a doctor, avoid self-medication.