The redness and swelling at the root of the thigh for treatment needs to be based on the causes that arise: the first condition may be due to excessive walking, wearing underwear that rubs more against the skin, especially sweating more, the clothes will become harder and produce too much friction on the skin, causing skin inflammation and redness at the root of the thigh. This situation must let the skin fully avoid external stimulation, wear looser clothes, keep the skin dry, otherwise it will lead to the gradual aggravation of the inflammation. You can apply topical dexamethasone cream to relieve the local skin inflammation. In the second case, there may be a sebaceous cyst in the skin at the root of the thigh. This is due to poor local sweat excretion causing the infected material in the sebaceous gland to become a cyst, resulting in significant redness and pain at the root of the thigh. In this case, it is best to go to the hospital for surgery to remove the local sebaceous cyst, remove all the infected material as well as the envelope completely, perform suturing, and generally remove the stitches in two weeks’ time. The third case may be trauma to the root of the thigh, in this case it is best to go to the hospital for a film examination to clarify the specific damage to the root of the thigh, for targeted treatment.