Itching at the base of the thighs may be a symptom of eczema, ringworm or contact dermatitis. It is necessary to consult a doctor in time to clarify the cause of the disease. 1. Eczema: the causes of eczema are complex and related to a variety of internal and external factors, such as mental stress, endocrine disorders, climate change and external stimuli are all triggering factors for eczema. It can lead to erythema, papules and itching on the thigh root. 2. Ringworm: It is caused by fungal infection, transmitted through direct or indirect skin contact, and may also be caused by fungal infection in other parts of the body. Fungus likes moist and hot environment, obese and diabetic people are easy to be infected with ringworm. 3. Contact dermatitis: it is a localized irritation or allergic reaction caused by skin contact with irritants or allergens, and contact dermatitis appearing at the root of the thighs may be an allergy to underwear materials, sanitary napkins, and so on. Thigh root itching persists unrelieved, need to go to the hospital in time to clarify the cause of the disease