The side effects of ringworm treatment in cats depends on the medication chosen but include nausea, changes in the white blood cells and possible liver disease, according to the Mar Vista Veterinary Hospital. Cats are most commonly given terbinafine or itraconazole instead of griseofulvin when it comes to oral medications, because these two newer drugs do not have as many side effects as griseofulvin, reports the VCA Animal Hospitals.
If a cat has contracted the Feline Immunodeficiency Virus then it should not be given the griseofulvin medication because the cat will be more susceptible to the life-threatening side effects of the drug. It has also been noted that Persian cats tend to develop the more serious side effects . Griseofulvin medication is given orally and is usually less expensive than the other options.
Itraconazole is another oral medication option but it is provided in huge capsules that most cats cannot swallow. Therefore, it has to be made into a special medication size and costs more. However, it does not have as extreme side effects and usually only gives a cat nausea.
A newer drug known as terbinafine is sometimes used, but it is extremely expensive when compared to griseofulvin and itraconazole so it is rarely administered. It is also not known to have any advantages over the other two medications, making it an unlikely choice for most owners and ringworm infected cats.