Fluconazole is an antifungal medication that veterinarians commonly prescribe off-label to treat certain fungal infections in cats and dogs. This medication comes in tablet and liquid suspension forms that pets take by mouth. The injectable form of the antifungal is only used in veterinary clinics. Side effects of fluconazole in cats and dogs can include vomiting, diarrhea, and poor appetite.
Certain fungal infections such as cryptococcosis, blastomycosis, and histoplasmosis
Fungal urinary tract infections caused by Candida
Valley fever (coccidioidomycosis)
Fluconazole is an azole antifungal. It works by destroying the protective outer covering of the fungus that’s causing the infection. The fungus can’t survive when its outer covering gets damaged.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Rare
Chills
clay-colored stools
dark urine
difficulty with swallowing
dizziness
fast heartbeat
general feeling of tiredness or weakness
headache
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
light-colored stools
loss of appetite
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
stomach pain, continuing
tightness in the chest
unpleasant breath odor
unusual tiredness or weakness
upper right abdominal or stomach pain
vomiting
vomiting of blood
yellow eyes and skin
Incidence not known
Black, tarry stools
blistering, peeling, or loosening of the skin
chest pain or discomfort
decreased urine
fainting
hoarseness
increased thirst
irregular or slow heart rate
joint or muscle pain
loss of bladder control
lower back or side pain
mood changes
muscle pain or cramps
muscle spasm or jerking of the arms and legs
numbness or tingling in the hands, feet, or lips
painful or difficult urination
pale skin
red skin lesions, often with a purple center
red, irritated eyes
seizures
sores, ulcers, or white spots in the mouth or on the lips
sudden loss of consciousness
swollen glands
unusual bleeding or bruising
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Fearfulness, suspiciousness, or other mental changes
seeing, hearing, or feeling things that are not there
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common
Belching
change in taste or bad, unusual, or unpleasant (after) taste
indigestion
stomach discomfort or upset
Incidence not known
Hair loss or thinning of the hair
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Different formulations available (tablets or orange-flavored liquid)
Can be given with or without food
Low chance of side effects
Not the first choice for treating some fungal infections, like ringworm
Long treatment time for some infections (weeks to months)
Your pet can take fluconazole with or without food. If your pet vomits when they take fluconazole on an empty stomach, try giving the medication with food. If they continue vomiting, contact your veterinarian.
Vomiting and diarrhea are common side effects of fluconazole. These side effects can put your pet at risk for dehydration. Put bowls of fresh water near areas of your house where your pet often goes to keep them hydrated. Contact your veterinarian if your pet doesn’t stop vomiting or having diarrhea.
Be careful to avoid being bit when you’re giving fluconazole to your pet, particularly dogs, that are taking this medication to treat blastomycosis. Although very rare, this fungal infection can spread to humans from dog bites. You won’t get blastomycosis from touching your pet though. Talk to your vet about ways to give this medication if your pet has blastomycosis and tends to bite when you give them medications.
Don’t stop giving your pet fluconazole until your vet tells you it’s okay to stop. Stopping this medication before the fungal infection is completely treated can make the infection more difficult to get rid of.
Tell your veterinarian if your pet has taken fluconazole before. Fungi can build resistance to the medication if it’s used over and over again to treat infections. This can make infections more difficult to treat.
If fluconazole is compounded for your pet, follow the directions that your vet and pharmacist give you about dosing and storage. The information for compounded formulations might be different from the human versions of this medication.
Tips for the liquid suspension form of fluconazole:
Store the liquid at room temperature (between 41°F and 77°F). Discard any unused medication after 2 weeks.
Don’t use household spoons to measure the dose for your pet since not all spoons are the same size. Use a measuring device like an oral syringe or a dosing cup to measure the dose instead. Ask your vet or pharmacist if you need these measuring devices.
Fluconazole can cause some serious health issues. This risk might be even higher for certain pets. If this worries you, talk to your veterinarian about other options.
Liver damage can happen in cats and in dogs that take fluconazole. In a study that specifically looked at how fluconazole affects liver function in dogs, some dogs had higher-than-normal liver enzyme levels on their blood test results. Having elevated liver enzyme levels can mean that the liver is irritated. Liver enzyme levels generally go back to normal after the vet lowers the fluconazole dose or after your pet stops taking the medication.
Signs of liver damage to watch out for in cats and dogs include yellowing of their eyes or skin, swelling around the stomach, vomiting, diarrhea, and low appetite or energy. If you notice signs of liver damage in your pet, contact your veterinarian, an emergency veterinarian, or a pet poison hotline immediately.
Fluconazole comes in tablets and a liquid suspension. It can sometimes be made or compounded into a form that fits your pet's needs.
Most times, dosing is based on your pet’s weight. The vet will determine the length of therapy based on the type of fungal infection and your pet’s response to fluconazole.
Cats: The dose is usually rounded to 50 mg by mouth every 12 or 24 hours. Your vet might use a different dose for your cat depending on what type of infection it is and how serious it is.
Dogs: The typical dose ranges 5 mg/kg to 10 mg/kg by mouth every 12 or 24 hours.
Fluconazole also comes in an injectable form that’s given through your pet’s vein (IV) by a veterinarian or technician.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
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