Red bumps on the inner thighs in winter are usually considered to be eczema, urticaria, contact dermatitis, and so on. 1. Eczema: Eczema is an inflammation of the superficial dermis and epidermis caused by a variety of internal and external factors, which can be manifested as erythema with papules and pimples, and is often itchy. 2. Urticaria: It is a limited edema that occurs in the skin and mucous membranes due to the temporary increase in vascular permeability, i.e., hives. Patients are often suddenly conscious of itching, soon appeared in the itchy parts of the size of the red masses, round, oval or irregular, can be isolated distribution or expansion of the fusion into a piece. 3. Contact dermatitis: contact dermatitis is an acute or chronic inflammatory reaction at the contact site caused by direct contact of the skin or mucous membrane with an exogenous irritant or allergic substance. The skin lesions are confined to the contact area, manifesting themselves as well-defined erythema, papules and small blisters. There may be other reasons for the red bumps on the inner thighs in winter, so it is recommended that the patient go to the hospital in time for treatment under the guidance of the doctor.