Donna, I asked my vet about this medicine and he has heard of other vets using it. He showed me his meds book and he looked it up and it said something about not using it on a cat that has had liver problems. Pepper had a slight liver problem last year. I think it was mainly due to not eating. This was another reason that I wanted him to have another bloodwork up done. I won't know these results until Fri. am at the earliset. The vet now prescibed Clindamycin Hydrochloride Drops. These are also fairly strong and kill many types of bacteria. I won't know the results of his nasal swab test until Sat. or Mon. of next week. I sure hope that Casey's new medicine works and that he feels better soon. Prayers are still going out to you Casey.