Only your doctor can answer the duration of treatment and dosage part as that would be decided after a clinical evaluation depending on the severity and extent of the lesions.
* Avoidance of sharing clothing, sports equipment, towels, or sheets.
* Washing clothes in hot water with fungicidal soap after suspected exposure to ringworm.
* Avoidance of walking barefoot, wearing of appropriate protective shoes to the beach and flip-flops/thongs in locker rooms.
* After being exposed to places where the potential of being infected is great , washing with an antibacterial and anti-fungal soap or one that contains Tea Tree Oil, which contains terpinen-4-ol.
The treatment options include - Topical antifungal agents such as terbinafine 1% cream (Lamasil) applied twice daily until symptoms resolve (usually 1-2 weeks). Terbinifine is not recommended for children < 2 years old or anyone with impaired hepatic function.
Systemically with oral medications, especially for scalp ring worm, or infection of the finger nails or toe nails.
Let us know if you need any other information and post us about how you are doing.