Stephanie Howe, DVM
By Stephanie Howe, DVM on May 23, 2023

In This Article


PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Fluconazole?

Fluconazole is an antifungal medication used to treat fungal and yeast infections in several species including: dogs, cats, horses, birds, small mammals, guinea pigs, rats, hamsters, ferrets, and reptiles. Fluconazole is often the first-choice medication for bodywide (systemic) fungal infections from organisms such as cryptococcus, Valley Fever (coccidioidomycosis), aspergillus, candidiasis, dermatophytosis (ringworm), histoplasmosis, and blastomycosis. Fluconazole may also be used for the treatment of yeast and ringworm infections of the skin, ears, and nails.

Depending on the pet that is being treated and the type of infection, certain antifungals may work better than others, like itraconazole, ketoconazole, or topical preparations. Your veterinarian will determine the best medication based on your pet’s needs and symptoms.

Fluconazole is FDA-approved for human use under the brand name Diflucan® and the generic fluconazole. Fluconazole is currently not FDA-approved as a veterinary medication. However, it is readily utilized in the veterinary field, and veterinarians can legally prescribe certain human drugs in animals in certain circumstances. This is called extra-label or off-label use because this use isn’t described on the drug label.

How Fluconazole Works

Fluconazole works as an antifungal medication by blocking the fungus’ ability to create an enzyme needed to produce their cell membrane. This stops the metabolism and growth of a given fungus. Fluconazole is often used when fungal infections occur in the nervous system or urinary tract, due to its ability to penetrate those spaces. Fluconazole is available in tablet or liquid suspension form.

Fluconazole is cleared primarily by renal excretion and should be administered with caution to pets with liver dysfunction. The dose of the medication may need to be reduced in pets with impaired renal function. Additionally, this medication should be used with caution in pets that are pregnant or nursing. Speak with your veterinarian about your pet’s condition and whether this medication is right for your pet.

In certain circumstances, your veterinarian may recommend a compounded formulation of fluconazole. Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug, such as if your pet has trouble taking pills in capsule form, the dosage strength is not commercially available, or the pet is allergic to an ingredient in the FDA-approved medication. Compounded medications are not FDA-approved. They are created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs. You can learn more about compounded medications here.

Fluconazole Directions

Follow the directions on the drug label or as provided by your veterinarian. Generally, fluconazole may be given with or without food. If your pet is experiencing digestive upset after being given this medication on an empty stomach, try giving it with a small meal.

Missed a Dose?

Speak with your veterinarian about what to do if you forget to give a dose of fluconazole. Generally, they may instruct you to give it when you remember or, if it is almost time for your pet’s next dose, to skip the missed dose and resume your normal dosing schedule. Do not give extra or double doses.

Fluconazole Possible Side Effects

Fluconazole is generally well tolerated in dogs and cats, but the following side effects may occur:

  • Loss of appetite

  • Vomiting

  • Diarrhea

  • Hair loss

  • Eye discharge

  • Dry skin

  • Lethargy

  • Liver irritation

Symptoms of liver irritation may include:

  • Vomiting

  • Loss of interest in food

  • Yellow gums, skin or whites of the eyes

Human Side Effects

While this is a human prescription medication, there are different dosages and side effects that can occur in humans.  If you accidentally ingest a medication prescribed for your pet, call your physician or the national Poison Control Center hotline at 800-222-1222.  


Specific monitoring or routine testing while your pet is on this medication may be recommended by your veterinarian depending on your pet’s individual needs, other medications they may be on, and/or the issue that initially caused your pet to be placed on this medication. If your pet is on Fluconazole long-term, your veterinarian may monitor your pet for changes in liver function.

Call Your Vet If:

  • Severe side effects are seen (see above)

  • Your pet’s condition worsens or does not improve with treatment

  • You see or suspect an overdose

  • You have additional questions or concerns about the use of fluconazole

Fluconazole Overdose Information

There is limited information on overdoses of fluconazole; only large overdoses are likely to cause a toxic overdose. Symptoms to monitor include shallow breathing, drooling, urinary incontinence, blue gum color, vomiting, and diarrhea.

If you suspect an overdose, immediately contact your veterinarian, seek emergency veterinary care, or contact an animal poison control center. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Fluconazole Storage

Fluconazole should be stored at controlled room temperatures below 86 F. Liquid fluconazole should be stored at room temperatures between 41–86 F; avoid freezing. Always confirm storage requirements by reading the label.  

Keep the container tightly closed to protect it from moisture and light.

Compounded medications should be stored according to the compounding pharmacy’s label.

Keep out of reach of children and pets.

Fluconazole FAQs

Is fluconazole considered an antifungal medication for dogs?

Yes, fluconazole is an antifungal medication often used in dogs to treat a wide variety of fungal infections in dogs.

Can fluconazole be prescribed for Valley Fever?

Yes, fluconazole is often used as a first-line treatment for Valley Fever (coccidioidomycosis).

How long should a dog be on fluconazole?

The amount of time that a dog should be on fluconazole is highly dependent on the type of fungal infection that is present. Treatment durations can range from weeks to months or even years depending on the infection. Your veterinarian will determine the best course of treatment for your pet.

No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content contained in this article is sourced from public sources or the manufacturer.

Featured Image: iStock.com/demaerre


KuKanich K, KuKanich B, Lin Z, et al. Clinical pharmacokinetics and outcomes of oral fluconazole therapy in dogs and cats with naturally occurring fungal disease. Journal of Veterinary Pharmacology and Therapeutics. 2020;43(6):547-556

Vaden SL, Heit MC, Hawkins EC, Manaugh C, Riviere JE. Fluconazole in cats: Pharmacokinetics following intravenous and oral administration and penetration into cerebrospinal fluid, aqueous humour and pulmonary epithelial lining fluid. Journal of Veterinary Pharmacology and Therapeutics. 1997;20(3):181-186

Ratzlaff K, Papich MG, Flammer K. Plasma concentrations of fluconazole after a single oral dose and administration in drinking water in cockatiels (Nymphicus hollandicus). Journal of Avian Medicine and Surgery. 2011;25:23-31

Ivey ES, Morrisey JK. Therapeutics for rabbits. Veterinary Clinics of North America: Exotic Animal Practice. 2000;3(1):183-220, vii


Stephanie Howe, DVM


Stephanie Howe, DVM


Dr. Stephanie Howe graduated from the University of Florida College of Veterinary Medicine in 2011, after receiving a Bachelor of Science...

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