Fluoxetine for Dogs (Canine Prozac) Good or BAD?

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Can Fluoxetine Harm Dogs?

Fluoxetine for dogs (also known by the brand name “Prozac”) is a medication that can be prescribed to help treat some behavioral and medical issues in dogs. 

fluoxetine for dogs

Like any medication, fluoxetine can cause harm and should only be used as prescribed by a veterinarian. However, in the case of fluoxetine being given as specified, the medication is likely to be very safe. 

Harm will usually only occur through overdose or if the medication is combined with another medicine that can cause adverse effects.

In this article, we are going to explain what fluoxetine is used for, any drug interactions, and side effects so that you feel fully informed before your pooch starts taking this medicine.

What Is Fluoxetine Used For in Dogs?

Fluoxetine is part of a larger group of medicines called selective serotonin reuptake inhibitors (SSRIs), which work to delay the body’s reuptake of serotonin. Serotonin is a neurotransmitter in the brain which helps with mood stabilization and helps with feelings of wellbeing and happiness

By preventing the reuptake of serotonin, the neurotransmitter sticks around a bit longer, enabling it to continue providing the positive feelings it elicits. Fluoxetine is a standard medicine for use in humans with anxiety disorders. In dogs, it helps with similar conditions.

Common conditions fluoxetine is used to treat in dogs include separation anxiety, thunderstorm phobias, generalized anxiety, urine marking, and compulsive disorders.

Pros and Cons of Prozac for Dogs With Anxiety

As with any medicine, there are reasons veterinarians prescribe fluoxetine, but that doesn’t mean it’s perfect. Unfortunately, there are some downsides to this medicine, and these are listed below.


  • It helps to alleviate anxiety in dogs which can stop negative behaviors (such as barking or aggression)
  • Allows dogs to be calm in situations where they would generally panic. This allows for appropriate behavioral modification to allow a dog to learn how to behave better.
  • It helps keep a calm home by allowing your pet to be calm and not cause destructive or loud negative behaviors and interactions.
  • It can help keep people and other pets safe by reducing some instances of aggression.


  • It takes four to six weeks to start working
  • May cause some side effects (see below)
  • It can be expensive to maintain your dog on medication, with more regular vet visits, medication costs, and potentially costs to see a behaviorist.
  • There is the potential for overdosing, although this is rare.

Fluoxetine For Dogs and The Associated Drug Interactions

Fluoxetine can interact with other drugs and cause unwanted side effects. If your dog is prescribed fluoxetine, make sure to discuss any other medications your dog is on with your veterinarian. This includes herbal supplements.

The drugs listed should be used with caution when given with fluoxetine: anticoagulants (e.g., Warfarin), diazepam, diuretics, insulin, flea collars, methadone, NSAIDs, tramadole, trazodone, St. John’s Wort, propranolol, aspirin, other SSRI’s, tricyclic antidepressants.

Is Prozac For Dogs FDA Approved?

Yes, fluoxetine has been approved “on label” for dogs for the treatment of separation anxiety. However, in other forms of behavioral modification, Prozac will be “off label,” meaning the FDA has not approved it for this reason. 

Veterinarians will commonly prescribe medicines “off label,” including fluoxetine. Still, it is essential to understand any risks associated with doing this and make sure to follow your veterinarian’s advice closely and look for possible side effects of the medicine.

The Side Effects of Fluoxetine in Canines

The most common side effects of fluoxetine include sleepiness and reduced appetite. 

Other less common side effects include vomiting,  diarrhea,  shaking, panting, vocalization, restlessness, becoming uncoordinated, weight loss, and drooling. Severe and rare side effects include seizures and aggressive behaviors.

If any of the side effects become unmanageable, chat to your veterinarian, there may be a decision to reduce the dose or, in more severe situations, stop the medicine altogether.

As a dog develops a tolerance for fluoxetine, you may notice the more mild side effects reduce anyway, so in some cases, the medicine may be continued and the side effects monitored.

Which Precautions Should You Be Aware Of?

As discussed in more detail below, a severe consequence of fluoxetine administration is serotonin syndrome which can be caused by an overdose of medicines that affect serotonin levels in the brain. 

Therefore, if your dog is on any other medications or supplements, be sure to discuss these with your veterinarian before beginning treatment with fluoxetine.

Dogs with other conditions such as diabetes mellitus or seizure disorders (e.g., epilepsy) are not usually prescribed fluoxetine. Also, dogs with liver or kidney disease may do poorly on this drug. 

If you know your dog has another condition affecting them, discuss this first with your veterinarian before treating it with fluoxetine.

Fluoxetine takes a long time to start working and will only work well in dogs with behavioral modification. Fluoxetine alone will not treat behavioral issues. If there isn’t an option to work on behavior in your dog, then fluoxetine may not be the best medication option.

Fluoxetine can continue to be in the dogs’ body for four to five weeks after discontinuing the drug. However, in some dogs, there can be signs of them no longer responding to fluoxetine. This can also occur in humans and may require a change in meds.

The dose that your dog starts on may not be the final dose they need. Behavioral modification drugs are usually started at a low dose and titrated up to help prevent overdose. There will likely be regular vet visits while the best quantity is found for your pet.

Signs of Fluoxetine Overdose in Dogs

In a rare but severe scenario, a dog that is given too many medications which cause serotonin accumulation can develop a condition called serotonin syndrome. This can occur when a dog is accidentally given too much fluoxetine, or they get ahold of the bottle and chew it.

An overdose of fluoxetine causes too much serotonin in the body and can cause fever, muscle twitching, and convulsions. If your dog becomes unwell while on fluoxetine, it is best to get them seen by a veterinarian as soon as possible and advise them that your dog is on the medicine.

What to do in an Emergency Situation

If your dog is unwell, it is recommended to contact your veterinarian for advice, especially if they have recently started taking fluoxetine. Your veterinarian can advise you on the appropriate next steps and let you know if your dog needs to be seen right away. If your regular veterinarian isn’t open, call an after-hours clinic.

puppy with veterinary ambulance

If your dog is having seizures or convulsions, is not responsive, or cannot stand, then don’t wait; just bring them to your veterinarian as soon as possible. If you have time, bring any medications your dog takes with you. 

Be careful not to become injured by your dog if they are having a seizure. If you aren’t sure you can do it safely on your own–get help first.

Properly Storing Fluoxetine For Dogs 

Fluoxetine is a severe drug and should be stored safely away from animals and people who might ingest the medicine. Make sure it is stored in a child-proof bottle away from moisture and light. Store it at approximately between 68℉ (20 ℃) and 77℉ (25℃). 

If the medication has been specially compounded for your pet, follow the directions on the label and make sure to use it before the expiry date, and dispose of any unused medication carefully. 

Suppose you don’t know what to do with unused medication. In that case, your veterinarian should be happy to dispose of it for you, do not flush tablets or throw them out in your household waste, as this can pose a risk to stray animals, wildlife, or even humans.

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Helen's journey in veterinary medicine is marked by her dedication to small animal practice and a thirst for diverse experiences. She graduated from Massey University in 2016, embarking on her career at a rural clinic in Canterbury, New Zealand, before venturing to the UK in search of new challenges. Helen's love for animals has always been at the core of her passion, and her dream of working with them has become a fulfilling reality.