The inner thighs are very dark in color and need to be treated with medication and physical therapy according to the cause of the disease. Common causes include hyperpigmentation and jock itch. 1. Hyperpigmentation: Long-term wearing of tight underwear or obesity may lead to repeated mechanical stimulation of the inner thigh skin for a long time, resulting in hyperpigmentation. Hydroquinone cream and arbutin cream can be applied locally to improve the symptoms, and those with obvious hyperpigmentation can use physical therapy, such as strong pulse light, to reduce the phenomenon of hyperpigmentation. 2. ringworm: ringworm is caused by dermatophyte infection, manifested as red spots, pimples, scales on the surface of the skin, accompanied by obvious itchy symptoms, due to repeated stimulation of inflammation, may make the inner thighs dark, can be applied locally antifungal drugs such as biphenylbenzazole cream, ketoconazole cream and so on. The dark color of the inner thighs may also have other causes, it is recommended to go to the hospital in a timely manner to improve the examination, to clarify the cause of the targeted treatment, the specific medication and treatment need to comply with the doctor’s instructions.