Written By hannah hollinger
Published: 12/01/2020Updated: 01/12/2022
Veterinary reviewed by Dr. Linda Simon, MVB MRCVS
Fluoxetine for Dogs | Wag!

Fluoxetine is an SSRI (selective serotonin reuptake inhibitor) antidepressant used for both humans and animals. For dogs, fluoxetine is used to treat behavioral disorders including separation anxiety, aggression, generalized anxiety,obsessive-compulsive disorders and inappropriate urination or marking. Often, fluoxetine is considered most effective when paired with an appropriate training method.


Fluoxetine for dogs is sold as individual tablets or capsules available in 10 mg, 15 mg, 20 mg, 40 mg, or 90 mg strengths. It is also available in liquid form. An average dose is:

The exact dosage depends on the condition it is being prescribed for, as well as the response of the dog to treatment.

Dosage instructions

Fluoxetine for dogs is administered orally once a day over a long period of time. This medication works slowly, and results may not be seen for 3 to 4 weeks, and often for up to 8 weeks. During this time, testing may be used to evaluate the effectiveness of this medication. Always talk with your veterinarian before discontinuing use as there may be unpleasant side effects.

This medication can be given with or without food. If your dog vomits when taking it on an empty stomach, give with a meal or treat. Do not feed your dog aged cheeses while taking fluoxetine.


Fluoxetine for dogs has shown varying amounts of success for several behavioral issues, and has been proven even more effective when combined with behavior modification training.One study showed a 59% success rate in treating fear aggression, anxiety, obsessive-compulsive behavior and self-mutilation when the medication was paired with a behavior modification plan.

 Another study that tested the efficacy of fluoxetine in both its human form of Prozac and the veterinary formulation of Reconcile for treating separation anxiety found a 72% improvement when used in conjunction with a behavior modification plan.

Two studies have also proven fluoxetine’s efficacy in treating compulsive and obsessive-compulsive disorders such as fly-biting and tail-chasing. Dogs who had taken fluoxetine were shown to be8.7 times more likely to see an improvement in compulsive behavior than those taking a placebo. A2015 study that treated dogs specifically for fly-biting saw a positive response in 100% of cases.

Side effects of Fluoxetine

There are several side effects associated with fluoxetine, including:

  • Lethargy

  • Insomnia

  • Decreased appetite

  • Vomiting

  • Diarrhea

  • Restlessness

  • Irritability

  • Panting

  • Increased vocalization

  • Increased salivation

  • Anxiety

  • Hyperactivity

  • Weight loss

  • Weakness

The following serious side effects warrant seeing the veterinarian right away if they appear:

  • Seizures

  • Tremors

  • Muscle Twitching

  • Blistered or peeling skin rash

  • Incoordination

  • Confusion

  • Aggression

  • Persistent or excessive vomiting

  • Fast Heartbeat

Once fluoxetine has been discontinued, the effects should disappear within a few days.


There are several considerations to note before starting a fluoxetine prescription. Do not give your dog this medication if they are allergic to fluoxetine, are under 6 months old, or are pregnant or lactating. Do not use a flea and tick collars when administering fluoxetine to your dog, and avoid feeding your dog aged cheeses.

Dogs with a history of seizures, diabetes mellitus, or severe liver disease should not take fluoxetine. Fluoxetine and MAO inhibitors should not be taken together, and need a period of time between their individual use in the same animal.

Fluoxetine for dogs is best used for behavioral issues in conjunction with behavior modification training.

Drug interactions

Fluoxetine hydrochloride is the active ingredient in the human drugs Prozac and Sarafem, and in the veterinary formulation of Reconcile. Fluoxetine may interact with the following medications:

  • Anti-anxiety medications (alprazolam, diazepam, buspirone)

  • Anticoagulants (warfarin)

  • Antidepressants (clomipramine, amitriptyline, imipramine, trazodone)

  • Antihistamine (cyproheptadine)

  • Antibiotic (isoniazid)

  • Anti-parasitic medication (amitraz)

  • Anti-seizure medication (phenytoin)

  • Beta blockers (propranolol, metoprolol)

  • Digitalis glycosides (digoxin)

  • Diuretics

  • Flea/tick collars (Preventic Collar)

  • Insulin

  • MAO inhibitors (anipryl, selegiline) 

  • NSAIDs (aspirin, carprofen, piroxicam, etodolac)

  • Opiate pain relievers (methadone, pentazocine, tramadol)

  • Sedatives (acepromazine)

  • St. John’s wort (which is toxic to dogs and should not be used)

Serotonin syndrome is a serious drug-reaction that is often caused by combining two medications that increase serotonin levels. The most common combination known to cause this condition are SSRI medications, such as fluoxetine, with MAO inhibitors. Symptoms of this syndrome can include tremors, dilated pupils, difficulty breathing, and elevated heart rate and blood pressure. 

Allergic reactions and sensitivity

If your dog develops an allergic reaction to fluoxetine, you may see symptoms such as a skin rash or hives, difficulty breathing, or a swelling in the throat, face, lips or tongue.Other common symptoms of an allergic reaction include head shaking, a sneezy or runny nose, intense scratching or diarrhea. Be sure to seek advice from your veterinarian right away if these symptoms appear when taking fluoxetine.

Frequently asked questions

Does fluoxetine require a prescription?

Fluoxetine for dogs does require a prescription from your veterinarian.

What do I do if I miss a dose of fluoxetine?

Give your dog the missed dose of fluoxetine when you remember. If it is close to the time the next dose is scheduled, then skip the missed dose and give the regularly scheduled dose on time. Never give your dog two doses of this medication at once.  

Will my veterinarian monitor my dog while taking fluoxetine?

Your veterinarian may not need to monitor your dog while taking fluoxetine, unless any adverse side effects or symptoms appear.

Can I give my dog my Prozac?

While the active ingredient in Prozac is the same as in veterinary formulations of fluoxetine, the dosages may be different. Consult with your veterinarian who will prescribe a veterinary formulation of fluoxetine that is made for canine dosing.

What should I do in an emergency?

If you suspect an overdose or allergic reaction, contact your veterinarian or local veterinary emergency clinic immediately.Signs of an overdose generally appear within 30 – 60 minutes of medication administration, and can include lethargy, excessive salivation, and seizures.

How is fluoxetine stored?

Keep medical formulations of fluoxetine at room temperature (between 68°F and 77°F)  in a closed container away from moisture and light.

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