Hello, Tinea corporis is a fungal infection of the body. I suggest my patients to consult a physician or a dermatologist for that. Yes, Ketoconazole soap can be used but the treatment requires local anti fungal creams for the infection. As you said, Terbinafine can be used orally for ring worm infection which is difficult to treat. I suggest my patients to consult a dermatologist who can treat such difficult ring worm infections. The skin doctor would analyse the infection first and would make a proper diagnosis and treat appropriately. I suggest to consult as early as possible and not to delay for any complications like abscess to develop. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Muhammad Azhar Hussain, Internal Medicine Specialist