Red bumps on the root of the thigh with itching are considered as follows: 1. Insect bite dermatitis, which is an allergic reaction due to mosquito bites. In clinical treatment, you can take oral Epinastine hydrochloride capsules, combined with Olopatadine hydrochloride tablets, topical halomethasone ointment, with zinc oxide boric acid ointment application; 2, stage II syphilis rash, is due to syphilis spirochete infection caused by sexually transmitted diseases. In clinical treatment, intramuscular injection of benzathine penicillin sodium injection is needed, while avoiding sexual intercourse with others, leading to its causing the corresponding infection; 3, dermatofibroma secondary to bacterial infection, this disease belongs to the benign swelling of the skin, excessive scratching can cause red bumps and itching. Treatment requires the application of fusidic acid ointment, and after the self-conscious symptoms subside, laser cautery is chosen for treatment.