Suppression of the bone marrow is a rare, but potentially fatal, complication of griseofulvin therapy. Toxicity cannot be predicted and may appear without warning. Itraconazole is one of the newer drugs being used to treat ringworm. It is not approved for use in cats, but it is generally considered safe and effective. The cost of the drug is prohibitive in some cases.
Some reports indicate that it is equal or possibly superior to griseofulvin in achieving a cure.
It may offer the advantage of preventing fungal spores from adhering to the dead layer of the skin. For cats who cannot tolerate griseofulvin or are not cured by it, itraconazole is a good choice. Baths using an antifungal shampoo. A bath should be given 3 times on an every other day schedule. Bathe exposed but unaffected pets once.