Dear Elisa, This sounds like a very extensive and unusual "ringworm". I think that there are other diagnosis that could be considered such as psoriasis, contact dermatitis, numular eczema or even pityriasis rosea or inversus. Was a fungal scraping done to confirm this diagnosis? Ketoconazole is a heavy duty oral antifungal which can produce idiosyncratic hepatocellular dysfunction and effects on various hormones. I would like to be very sure of the diagnosis before commencing a long term treatment regimen in any patient, let alone a lactating mother. Shirley Gross M.D.,C.M., C.C.F.P. Edmonton Breastfeeding Clinic