Cat Ringworm Medicine

Ringworm medicine is available for your cat, sometimes with a prescription from your veterinarian. Ringworm is a fungal infection affecting your cat's hair and skin. It starts as a small round hairless lesion. As the lesion grows, the center will become scaly and small pustules will develop. There are two methods for diagnosing ringworm that your veterinarian may use. One method is a Wood's lamp and the other method is a fungal culture. Once your veterinarian has diagnosed your cat with ringworm, there are several options that can be taken.

Topical Creams, Lotions or Sprays

In mild cases of ringworm, your veterinarian may use topical creams, lotions or sprays that contain an anti-fungal ingredient. This is more effective when treating short haired or shaved cats. In severe cases, topical and oral medications are used together.


Thiabendazole is the active antifungal ingredient in Tresaderm. Thiabendazole is used in conjunction with an antibiotic and a steroid to relieve pain and itching from ringworm. Possible side effects can be the absorption of the steroid into circulation, causing suppression of the adrenal glands. Do not use this product on pregnant cats. Thiabendazole is prescribed in a liquid form and is applied with a dropper to the affected areas.


A lime-sulfur dip can be used to treat ringworm and is very useful if your cat has multiple lesions. The dip is recommend every four to five days and is usually done by your veterinarian. This treatment may cause temporary yellowing of your cat's coat.

Oral medications

Oral medications are prescribed for severe cases of ringworm. These are usually given until two negative cultures are taken at least one week apart.

  • Fulvicin: Griseofulvin is the active antifungal ingredient in Fulvicin. Griseofulvin is the drug of choice for treating ringworm in cats. It's known to suppress cell formation. Side effects of griseofulvin are vomiting, diarrhea, lethargy and decreased appetite. Griseofulvin is not to be given to pregnant or FIV positive cats. Griseofulvin is prescribed in capsule, tablet and liquid form.
  • Sporanox: Itraconazole is the active ingredient in Sporanox. It is similar to griseofulvin but is less often used because of the cost. Side effects are nausea, jaundice, vomiting and diarrhea. This medication is not to be used on pregnant cats. Itraconazole is not approved by the Food and Drug Administration but can be prescribed legally as an extra-label drug. Itraconazole is prescribed only in capsule form.
  • Nizoral: Ketoconazole is the active antifungal ingredient in Nizoral. Ketoconazole inhibits the growth of fungal organisms. Side effects are decreased appetite, vomiting, diarrhea, jaundice, possible drying of coat and suppression of hormone synthesis, which may affect reproduction. This medication is not to be used on pregnant cats. Ketoconazole is not approved by the Food and Drug Administration but can be prescribed legally as an extra-label drug. Ketoconazole is prescribed in tablet form.