Fluconazole

By Rania Gollakner, BS, DVM

Medications

What is fluconazole?

Fluconazole (brand name: Diflucan®) is an antifungal medication used to treat fungal infections, especially for infections in the brain or spinal cord.

Its use in cats, dogs, and small mammals to treat fungal infections is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is fluconazole given?

Fluconazole is given by mouth in the form of a tablet or liquid suspension. It also comes in an injectable form, that is administered in hospital by your veterinarian.

Both the tablets and the liquid can be given with or without food, but if your pet vomits or acts sick after taking the medication, give the medication with a small meal or treat. Do not skip doses and follow the dosing instructions carefully. This medication can take up to a few weeks before full effects are noted, but gradual improvements are usually noticeable after a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

When taking fluconazole, the most common side effects include gastrointestinal effects such as low appetite, vomiting, diarrhea, or soft stools. Especially with long-term use, liver toxicity can occur. 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?

Fluconazole should not be used in pets that are allergic to it or similar medications. Use with caution in pets with liver or kidney disease. It should also be used with caution in pets that are pregnant or nursing, and the benefits should outweigh the potential risks.

Are there any drug interactions I should be aware of?

While using fluconazole, the following medications should be used with caution: amphotericin B, benzodiazepines, buspirone, cimetidine, cisapride, colchicine, corticosteroids, cyclophosphamide, cyclosporine, diuretics (thiazides), fentanyl, losartan, macrolide antibiotics, methadone, NSAIDs, quinidine, rifampin, sildenafil, theophylline/aminophylline, tricyclic antidepressants, sulfonylurea antidiabetic agents, vincristine/vinblastine, and warfarin.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

When using fluconazole long term, your veterinarian will monitor your pet for changes in liver function and to be sure that the medication is working. Monitor your pet for any side effects and contact your veterinarian if any are noted.

How do I store fluconazole?

Fluconazole tablets and the powder used to make the liquid suspension should be stored in a tight container, at room temperature (below 30°C or 86°F). Once the powder is mixed with water, it can be refrigerated but avoid freezing it. Discard any unused liquid medication after two weeks.

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.

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