An itchy red rash on the inner thigh skin is considered as the following possibilities: 1. It is a common form of ringworm, mainly caused by fungal infection. Clinical tests for fungal microscopy, as well as fungal culture are needed first to clarify the diagnosis. If the diagnosis is clear, topical terbinafine hydrochloride spray can be used twice a day. And after the medicine dries and crusts, you can apply topical amorolfine hydrochloride ointment for treatment; 2. Consider the possibility of eczema, which may be mainly due to allergic reaction caused by wearing chemical underwear, or applying poor quality emollient cream. In clinical treatment can be topical Denide ointment, 1:1 mixed zinc oxide borate ointment applied, while oral chlorpheniramine maleate tablets treatment.