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Fluoxetine for Companion Animals


General Drug Information and Indications
How to Give this Medication
Side Effects
Drug Interactions
More Information About This Medication
Search for Available Dosage Forms

General Drug Information and Indications

Fluoxetine is the generic name for the human anti-depressant medication, Prozac. It is used in dogs, cats, and birds for behavior problems such as separation anxiety, aggression, obsessive-compulsive behaviors and inappropriate elimination. Fluoxetine is FDA approved for use in separation anxiety in dogs. All other uses of fluoxetine in dogs, cats and birds are not FDA approved, but there is considerable experience with the use of this type of medication for small animal behavior problems. When the appropriate form or dose of this drug is not available through a veterinary pharmaceutical manufacturer, it may be compounded by a specialty pharmacy.

How to Give this Medication

Give this medication to your pet exactly as your veterinarian prescribes. If you miss giving your pet a dose of fluoxetine, give the next dose as soon as you remember or, if it is close to the next scheduled dose, return to the regular schedule. Do not double dose in order to catch up.

Fluoxetine must be given for 4-8 weeks before the full effect of the drug can be seen. Do not discontinue this drug suddenly. Your veterinarian will advise you on how to taper the dose at the end of treatment.

Fluoxetine can be given with food, which may help stomach upset.

Wash your hands after giving your pet this medication.

Side Effects

Be sure to discuss any side effects with your veterinarian immediately.

The most common side effects in dogs are sedation and loss of appetite. Other side effects include behavior changes such as anxiety, irritability, hyperactivity, and insomnia. Aggression is a very uncommon but serious side effect. If your dog shows any signs of aggression, you should get in touch with your veterinarian immediately. Seizures are a rare side effect; should your pet have a seizure, you should contact your veterinarian immediately.

Loss of appetite and behavior changes (anxiety, irritability, hyperactivity/insomnia, and changes in elimination behavior) are the most commonly reported side effects in cats. Appetite loss is common enough in cats that you may want to monitor your cat’s appetite and weight.

A skin rash may occur at the site of transdermal application.


Keep this and all drugs out of reach of children. Fluoxetine is a prescription drug and should be used according to your veterinarian’s directions. It should only be given to the animal for which it was prescribed. Do not give this medication to a person.

Fluoxetine is usually not prescribed for animals with diabetes mellitus or animals that have a history of seizures. Dogs or cats with liver problems may need a reduced dose.

Fluoxetine is present in the blood for 4- 5 weeks after discontinuing the drug

Just like in humans, some animals may stop responding to fluoxetine. In that case, your veterinarian may suggest trying a different medication in the same family of drugs.

Do not give yoru pet aged cheeses because they can cause a potentially life-threatening drug reaction.

Drug Interactions

Be sure to review with your veterinarian any medications or supplements your pet may be receiving. There are many possible drug interactions listed for fluoxetine in dogs and cats. Because there is much more experience with the use of fluoxetine in humans, some of these possible drug interactions are mentioned due to experience in humans, but they have not been studied in animals.

Serotonin syndrome is a rare but potentially life-threatening drug reaction caused by too much serotonin accumulation. This rarely occurs in animals but could occur if an animal is receiving fluoxetine with any of the following drugs: MAO inhibitors including amitraz (found in some flea/tick collars and dips) and selegiline, buspirone, isoniazid, pentazocine, or tricyclic anti-depressants. Symptoms include neuromuscular hyperactivity, hyperthermia, autonomic hyperactivity, and altered mental status. There should be a 2-5 week separation between any of these drugs and fluoxetine.

Other potential drug interactions includes; acepromazine, cyproheptadine, diazepam, alprazolam, diuretics, insulin, isoniazid, phenytoin, propanolol, metoprolol, tramadol, diuretics, trazodone, warfarin.


Signs of overdose in dogs and cats resemble those discussed under side effects: lethargy, hypersalivation and agitation. Seizures may occur in dogs that have received a massive overdose.

If you suspect your pet or another animal was overdosed accidentally or has eaten this medication inadvertently, contact your veterinarian or the A.S.P.C.A.’s Animal Poison Control Center at 888.426.4435. Always bring the prescription container with you when you take your pet for treatment.

If you or someone else has accidentally ingested this medication call the National Capital Poison Center at 800.222.1222.


Different strengths or dosage forms of fluoxetine may have different storage requirements. Read the labeling or ask your pharmacist for the storage requirements of the prescription you receive.

More Information About This Medication

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI). Serotonin is the neurotransmitter that is responsible for facilitation of social interactions, general awareness, coping mechanism, and adaptability. Drugs like fluoxetine increase the blood level of serotonin. Many other anti-depressant drugs are also SSRIs. These drugs are commonly prescribed for humans as a part of the treatment of depression, anxiety disorders, compulsive disorders, and difficulty managing aggression.

The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease. 

Wedgewood Pharmacy compounded veterinary preparations are not intended for use in food and food-producing animals.
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About the Author

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.