Prozac Side Effects for Dogs
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Dogs feel many emotions, such as anxiety, stress, and depression, just like people.
But since dogs cannot tell us how they feel, their emotions often show up as behaviors like chewing, pacing, or having accidents in the house.
The same medication that helps people with anxiety and depression can also help dogs who are stressed, lick themselves too much, or keep marking in the house.
However, any medication strong enough to change mood can have side effects, so it is important to know what they are before starting.
What's Prozac Used For?
Prozac is given to dogs to help with anxiety and depression. It increases serotonin in the brain, which helps dogs feel calmer and more balanced.
Vets often use Prozac for separation anxiety, fears like thunderstorms or certain people, compulsive actions, aggression, general anxiety, and too much urine marking.
It should be used with behavior training, not by itself. Without training, Prozac usually does not work as well.
What Are Prozac’s Side Effects?
Like most medications, Prozac can cause side effects. Some are more serious, while others are mild. It helps to know what side effects your dog might experience if they take Prozac.
Here are some side effects dogs may have:
- Loss of appetite
- Seizures
- Diarrhea
- Insomnia
- Vomiting
- Aggression
- Itching
- Liver damage
1. Loss of appetite
Fluoxetine changes serotonin levels, which help control appetite. This is why loss of appetite is one of the most common side effects, especially during the first few weeks as your dog gets used to the medication. Some dogs may also lose weight while taking it.
Mild decreases in appetite often go away on their own. If your dog won’t eat for more than a day or two, or keeps losing weight, call your vet.
2. Drowsiness or low energy
Fluoxetine changes brain chemistry and can make some dogs feel sleepy or have less energy.
This side effect is usually most noticeable at the start of treatment or after a dose increase. Most dogs adjust within a few weeks. If your dog still seems very tired, let your vet know.
3. Vomiting
Fluoxetine can upset the stomach, especially when your dog first starts taking it. Vomiting is most common soon after beginning treatment.
If your dog vomits once in a while and it’s mild, it’s usually not an emergency. But if vomiting happens often or doesn’t stop, contact your vet right away.
4. Diarrhea
Diarrhea, like vomiting, often means your dog’s digestive system is getting used to the medication. It’s most likely in the first few weeks. If it’s mild and goes away quickly, you can watch your dog at home. If it’s severe or doesn’t stop, call your vet.
5. Insomnia or restlessness
Serotonin affects sleep, so some dogs may become more alert or restless instead of calmer. This can happen more often if the dose is given later in the day. Try giving the dose earlier, but only with your vet’s approval. Let your vet know if your dog keeps having trouble sleeping.
6. Itching
Some dogs have mild skin irritation, but the cause isn’t clear and it doesn’t seem to affect any specific group more than others. Watch for scratching that gets worse or causes skin damage, and contact your vet if you notice these signs.
7. Shaking or mild tremors
Low-level tremors can result from fluoxetine’s effect on the nervous system and can appear at any point in treatment.
Keep a close eye on any shaking or tremors, as they can sometimes be an early sign of a more serious problem. Write down when they happen and how long they last. If they get worse, don’t stop, or happen with other symptoms, contact your vet right away.
8. Seizures
This is the most serious risk associated with Prozac.
Fluoxetine can make seizures more likely in dogs that are already at risk, such as those with a history of seizures or epilepsy. These dogs usually should not take this medication. Seizures are rare in dogs with no history, but they can still happen.
Any seizure is an emergency; contact your vet or an emergency clinic immediately.
9. Aggression or Increased Anxious Behavior
In some dogs, changes in serotonin can make anxiety or agitation worse instead of better. This can happen at any time and isn’t always related to the dose or how long your dog has been taking Prozac. If you notice this, tell your vet. They may change the dose or suggest a different medication.
10. Liver Damage
Fluoxetine is processed by the liver, so in rare cases it can cause liver problems. Dogs with liver disease or those taking Prozac for a long time are at higher risk. Vets usually check liver health before starting Prozac and may suggest regular blood tests. Watch for signs like yellow gums or eyes, tiredness, or loss of appetite, and tell your vet right away if you see them.
11. Unsteady Gait (Ataxia)
If your dog seems wobbly or loses coordination, this could be a serious reaction to the medication. It can happen at any time. Contact your vet right away instead of waiting to see if it gets better.
Most of these side effects show up in the first few weeks as your dog’s body adjusts to the medication, and many fade on their own once that adjustment period passes.
The more serious side effects, like seizures and liver damage, are rare. They usually happen in dogs with existing health problems or those taking Prozac for a long time.
This is why vets ask about your dog’s medical history before prescribing Prozac. They may also recommend bloodwork for dogs taking it long term.
Keeping a simple log of any changes you notice, even small ones, can help you spot patterns early and give your vet helpful information at your next visit.
Prozac’s Uncommon Serious Side Effects
If you notice ongoing weight loss, loss of appetite, tremors, seizures, increased aggression, or anxious behavior, these are serious and should not be ignored. Insomnia may also occur and cause problems. Changes in blood glucose can make it harder for people with diabetes to manage their condition.
What Is The Typical Prozac Dosage For Dogs?
A veterinarian will determine your dog’s Prozac dosage based on their body weight. In general, the dosage is 1 mg to 2 mg per kilogram of body weight given once a day.
The table below shows the average dosage of fluoxetine for dogs by weight.
| Dog weight | Prozac dose |
|---|---|
| 10 lbs | 5 mg |
| 20 lbs | 10 mg |
| 30 lbs | 15 mg |
| 40 lbs | 20 mg |
| 50 lbs | 25 mg |
| 75 lbs | 37.5 mg |
| 100 lbs | 50 mg |
Your dog’s dosage may vary depending on other health conditions they have, what medications they take, and other factors. A veterinarian will be able to determine the correct amount.
Drug Interactions You Should Watch For
Fluoxetine raises serotonin levels in the brain, so combining it with other serotonin-boosting substances can trigger serotonin syndrome, a dangerous and potentially life-threatening buildup.
Fluoxetine should never be combined with:
- MAO inhibitors like selegiline or amitraz, the highest-risk combination
- Tramadol
- Clomipramine or amitriptyline
- Trazodone
- Buspirone
Watch out for hidden exposure too. Amitraz shows up in some flea and tick collars, and calming supplements often contain tryptophan or 5-HTP, both of which convert into serotonin in the body.
Always tell your vet about every medication, supplement, and topical product your dog uses, even ones that seem unrelated. Watch for agitation, a fast heart rate, muscle twitching, or tremors, and call your vet immediately if you notice any of these.
Choose CBD As A Natural Alternative
If you’re worried about Prozac’s side effects, you might be looking for gentler alternatives. Many pet owners try CBD as a natural supplement for dogs with mild to moderate anxiety.
While research is ongoing, recent studies show that CBD may help dogs feel calmer by working with the endocannabinoid system and supporting serotonin, which affects mood and stress.
Owners often use CBD to help with:
- Anxiety and stress
- Separation anxiety
- Noise phobias
- General nervousness
CBD is usually well tolerated compared to Prozac. The most common side effect is mild drowsiness, especially at higher doses, and serious side effects are rare.
If your vet recommends CBD for your dog, Innovet’s PurCBD Oil is a great option.
You can easily adjust the dose, and it can go right into your dog’s food or be given by mouth to fit your dog’s needs.
→ Shop 100% Full Spectrum Golden Hemp CBD Oil for dogs here
If your dog likes treats, Innovet’s CBD Dog Treats offer the same calming benefits in a tasty chew that many dogs enjoy.
→ Shop InnovetPet’s Advanced Calming Chews and Treats here
No matter which option you pick, choose CBD products made from organic hemp and tested by third-party labs to make sure they are high quality and consistent.
Always talk to your veterinarian before starting CBD or any supplement, especially if your dog is on prescription medicine.
FAQ
Is Prozac the same for dogs and humans?
When a veterinarian prescribes fluoxetine for your dog, it is the same medication humans take. But human dosages are typically higher than dosages for dogs. A human dosage or the wrong dosage of Prozac could be toxic to dogs.
Is Prozac Safe for Dogs?
Prozac can be safe for dogs, but only if a vet prescribes it. Dog doses are very different from human ones, so never give your dog Prozac meant for humans as this could cause an overdose.
Prozac can be addictive, so vets usually suggest slowly reducing the dose instead of stopping all at once. Drowsiness is common, so watch your dog closely, especially at the beginning.
If you think Prozac might help your dog, talk to your vet first instead of deciding on your own.
How Long Does Prozac Take to Work?
Prozac takes time to build up in your dog's system, so you might not see changes for a few weeks. This is a good time to start new routines and training, since they work best with the medication.
Every dog is different, so keep track of any changes you see and let your vet know if your dog is not getting better.
Sources
The use of fluoxetine by veterinarians in dogs and cats
Long-term consequences of chronic fluoxetine
Classics in Chemical Neuroscience
The use of fluoxetine by veterinarians in dogs and cats
Fluoxetine in Dogs and Cats
Fluoxetine (Reconcile, Prozac)
Approved by:
Dr. Ivana Vukasinovic
Doctor of Veterinary Medicine, University of Belgrade
Ivana Vukasinovic grew up in Serbia and attended the University of Belgrade where she received a degree in Veterinary medicine in 2012 and later completed surgical residency working mostly with livestock. Her first year of practice was split between busy small animal practice and emergency clinic, and after two more years of treating many different species of animals, she opened her own veterinary pharmacy where an interest in canine and feline nutrition emerged with an accent on fighting animal obesity. In her free time, she acts as a foster parent for stray animals before their adoption, likes to read SF books and making salted caramel cookies.
Thanks for stopping by!
P.S. We Love You!
Sincerely,
The Innovet Team
Please do not ask for emergency or specific medical questions about your pets in the comments. Innovet Pet Products is unable to provide you with specific medical advice or counseling. A detailed physical exam, patient history, and an established veterinarian are required to provide specific medical advice. If you are worried that your pet requires emergency attention or if you have specific medical questions related to your pet’s current or chronic health conditions, please contact or visit your local/preferred veterinarian, an animal-specific poison control hotline, or your local emergency veterinary care center.
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