Overview of Griseofulvin (Fulvicin®) for Dogs and Cats

Griseofulvin, also known as Fulvicin®, is an antifungal drug that is incorporated into the hair shaft and inhibits the growth of fungal organisms in dogs and cats.

Griseofulvin is not related to other antifungal drugs, such as itraconazole (Sporanox®) and ketoconazole (Nizoral®).

Griseofulvin is effective only against fungal organisms that affect the skin and hair. These fungi, which cause skin infections (dermatophytes), are commonly known as “ringworm” and toenail infections.

Griseofulvin is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.

Brand Names and Other Names of Griseofulvin

This drug is registered for use in humans and animals.

Human formulations: Fulvicin® (Schering-Plough), Grisactin® (Wyeth-Ayerst) and Grifulvin V® (Ortho)

Veterinary formulations: Fulvicin® (Schering-Plough)

Uses of Griseofulvin for Dogs and Cats

Griseofulvin is used in both dogs and cats to treat infections caused by fungi. These infections may affect the skin, hair or claws.

Griseofulvin is not effective against infections caused by bacteria, parasites (intestinal worms), mites or viruses.

Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, griseofulvin can cause side effects in some animals.

Griseofulvin should not be used in animals with known hypersensitivity or allergy to the drug.

In cats, griseofulvin has caused suppression of the blood-forming cells. A veterinarian should check the blood count when griseofulvin is administered to cats for prolonged periods.

Griseofulvin may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with griseofulvin. Such drugs include phenobarbital and coumarin (wafarin).

Griseofulvin may cause nausea and decreased appetite in animals.

In cats, griseofulvin causes severe birth defects (teratogenic effects, developmental anomalies). Griseofulvin should never be administered to pregnant cats.

How Griseofulvin Is Supplied

Griseofulvin is supplied in capsules (250 mg), tablets (250 mg and 500 mg) or as a 25 mg/ml liquid oral suspension.

Dosing Information of Griseofulvin for Dogs and Cats

Medication should never be administered without first consulting your veterinarian.

The usual dose in dogs is 25 mg per pound (50 mg/kg) every 24 hours orally, however in refractory infections higher doses have been administered. It is common for fungal infections to require several weeks of treatment.

Due to the risk of side effects in cats, Griseofulvin is generally not recommended. When used in cats, the dose is the same as dogs. 

Griseofulvin is absorbed orally better when it is administered with some food or the morning meal. Do not administer on an empty stomach.

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.