The darkening and itching on both sides of the thighs may be caused by localized friction, ringworm and other reasons, which need to be treated with retinoic acid ointment and antifungal medication for the specific cause. 1. Local friction: The inner thighs are easily pigmented due to walking and long-term friction with underwear, causing the inner thighs to become black and occasionally itchy. You can wear loose clothes and pants to avoid repeated friction, and if necessary, follow the doctor’s instructions to use topical retinoic acid ointment and other drugs to improve the local coloration. 2. ringworm: ringworm is generally caused by fungal infection, mainly to local erythema, papules, scales, etc. as the main manifestation of the disease recurrence or recession period can lead to the local skin black, the treatment is mainly to the local topical antifungal treatment, such as miconazole nitrate cream, terbinafine cream, etc., if necessary, can be orally antifungal drugs, such as itraconazole, terbinafine and so on. There are many other reasons why the thighs are black and itchy, it is recommended to go to the hospital in time, to clarify the cause of the disease, under the guidance of the doctor to carry out active treatment, do not take medication without authorization, to avoid adverse consequences.