Itchy red bumps on the sides of the thighs may be caused by ringworm, papular urticaria and other causes. 1. ringworm: ringworm is a fungal infectious skin disease that occurs in the groin, buttocks, thighs, perineum and other parts of the body, manifesting itself as a ring-shaped or semi-ring-shaped erythema on the surface of the skin that develops from the inside to the outside, the surface is scaly, and the edges often have pimples, pimples, herpes, and blisters, accompanied by varying degrees of itching symptoms. 2. papular urticaria: when the sides of the thighs by insect bites, such as fleas, lice, mites, mosquitoes, etc., may lead to the human body to appear allergic reaction, thus triggering papular urticaria, manifested as the skin surface appears in clusters or scattered wind ball like pimples, the top of the small blisters, accompanied by intense itching symptoms. Itchy red bumps on both sides of the thighs may also have other causes, it is recommended that patients go to the hospital in a timely manner to improve the examination, to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment.