Both sides of the thighs have a red rash, consider eczema, ringworm and other diseases caused by, it is recommended that patients go to the hospital in a timely manner to clarify the cause of the disease, under the guidance of the doctor, topical glucocorticoid drugs, antifungal drugs treatment. 1. Eczema: Eczema is an inflammatory skin disease. Abnormal immune function and impaired skin barrier function may lead to eczema. Red rashes on both thighs may be caused by eczema. Patients can follow the doctor’s instructions to use hydrocortisone cream, mometasone furoate gel and other glucocorticoid drugs for treatment. 2. Ringworm: It is caused by pathogenic fungi invading the inner groin and causing ring or semi-ring lesions. Patients can follow the doctor’s instructions to use naftifine ketoconazole, econazole and other antifungal drugs for treatment. Rash on both thighs may also be other diseases, should be timely to the hospital, under the guidance of the doctor’s medication.