What is griseofulvin?
Griseofulvin (brand names: Fulvicin®, Gris-Peg®, Grisovin®) is an antifungal used to treat ringworm and other skin, hair, and nail fungal infections.
Its use in cats, dogs, small mammals, and horses to treat fungal skin infections is often off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine.
“Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada.
In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label. .
How is griseofulvin given?
- Griseofulvin is given by mouth in the form of a tablet or liquid suspension.
- Give with fatty food, such as cheese, cream, butter, or corn oil.
- Measure liquid forms carefully.
- If you are pregnant, wear gloves while giving this medication, wash hands thoroughly after administration, and avoid inhaling any dust from split or crushed tablets.
This medication can take up to a few weeks before effects are noticeable, and at times improvement may not be visible outwardly.
What if I miss giving my pet the medication?
If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.
Are there any potential side effects?
At proper dosages, side effects are uncommon in dogs. In cats, side effects are more common. Griseofulvin may cause the following side effects:
- Lack of appetite
- Vomiting
- Diarrhea
- Sunlight sensitivity (less common)
- Itchiness (less common)
Serious adverse reactions may occur. If any of the following signs develop, stop giving griseofulvin and contact your veterinarian immediately:
- Abnormal bleeding
- Pale gums
- Weakness
- Incoordination
- Collapse
- Fever
- Yellowing of the skin, eyes, or gums
- Severe vomiting
- Continued lack of appetite
- Severe sleepiness
- Severe skin rashes or wounds
Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
DO NOT USE griseofulvin in:
- Pets that are allergic to it
- Pets that are pregnant
- Pets that are breeding males
- Pets that have severe liver disease
- Cats with FIV or FeLV (test cats for viral infections prior to starting this medication)
USE WITH CAUTION in:
- Kittens (they are more susceptible to side effects)
- Pets that are lactating (safety has not been established; consider using a milk replacer)
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with griseofulvin, including:
- Aspirin
- Cyclosporine
- Phenobarbital
- Theophylline
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
Is any monitoring needed with this medication?
- Your veterinarian may monitor your pet to be sure that the medication is working, primarily by performing fungal cultures.
- Your veterinarian will likely monitor blood cell counts prior to starting the medication and then every 1–3 weeks during therapy.
- Your veterinarian may monitor liver enzymes.
- At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
How do I store griseofulvin?
- Store this medication at room temperature, ideally between 59°F and 86°F (15°C and 30°C) and do not exceed 104°F (40°C).
- Store in a tight container and protect from light.
- Keep the container out of reach of children and pets.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
