When Jazz had ringworm I didn't see my favorite vet but one of the others on staff. After a week or so of just using the ointment and sprays he prescribed an oral med for her that I had to have mixed by a pharmacist. The only one who made this was in a neighboring town and I had it mailed to me, very expensive. I gave it to her twice a day for several weeks. When I took her back in for a check up I got to see my favorite vet. He went through the roof when he found out the other vet prescribed the oral med. He said it was too dangerous to give to a kitten and told me to stop giving it to her immediately. After researching it better on the internet I found out it could cause serious liver and kidney damage as you stated in your post. The next time I went to the vet I found out that doctor had been fired. I don't know if it was related but it sure makes me question the meds they prescribe for my furbabies now.