The most commonly used antifungal creams are Clotrimazole, Ketoconazole, Miconazole,
Terbinafine and Tolnaftate.
If there are several ringworm lesions or if the lesions are extensive, oral antifungal medications can be used. Because fungi prefer warm, moist environments, preventing ringworm involves keeping skin dry with the usage of talcum powder.
ref:http://en.wikipedia.