Fluoxetine (Reconcile/Prozac) for Dogs: Uses & Side Effects

See your vet immediately if your dog has a seizure, collapses, becomes severely agitated, shows tremors, or may have taken too much fluoxetine. Overdose and serious drug interactions can be dangerous.

This article is educational only. Fluoxetine should only be used under your vet's guidance because the right dose, timing, and monitoring plan depend on your dog's age, weight, medical history, behavior diagnosis, and other medications.

Do not start, stop, or change this medication on your own. Fluoxetine often takes several weeks to reach full effect, and stopping suddenly can create setbacks or side effects. Your vet may also pair medication with behavior modification, environmental changes, and follow-up visits.

Fluoxetine is a selective serotonin reuptake inhibitor, or SSRI. It changes how serotonin is handled in the brain, which can help some dogs feel less anxious and more able to learn calmer behaviors over time.

In dogs, the FDA-approved veterinary product is Reconcile, labeled for canine separation anxiety when used with a behavior modification plan. Human generic fluoxetine and brand-name Prozac may also be prescribed by your vet as extra-label options when that makes sense for your dog.

This is not a fast-acting sedative. Most dogs need daily dosing for several weeks before the full benefit is seen. That delay is important to know, because pet parents sometimes expect a same-day change and feel discouraged too early.

Fluoxetine is usually given by mouth as a tablet, capsule, chewable tablet, or liquid. Your vet may choose a commercial product or a compounded version if your dog needs a different strength or form.

The clearest approved use is separation anxiety in dogs. In that setting, medication works best when paired with behavior work such as gradual departures, enrichment, predictable routines, and avoiding panic-triggering situations when possible.

Your vet may also use fluoxetine extra-label for other behavior problems, including compulsive behaviors like flank sucking or lick-focused behaviors, generalized anxiety, fear-based reactivity, and some aggression cases. Medication does not replace training. Instead, it can lower the emotional intensity enough for learning and behavior change to happen.

Not every anxious dog needs fluoxetine, and not every behavior problem is anxiety. Pain, neurologic disease, cognitive changes, urinary issues, skin disease, and GI discomfort can all affect behavior. That is why a medical and behavior evaluation matters before treatment starts.

For the FDA-approved canine product, the labeled dose is 1 to 2 mg/kg by mouth once daily. Reconcile chewable tablets come in 8 mg, 16 mg, 32 mg, and 64 mg strengths. Your vet may use the labeled dose or adjust the plan based on your dog's response, side effects, and the condition being treated.

Fluoxetine is usually given once daily, with or without food. If your dog vomits on an empty stomach, your vet may suggest giving it with a meal or treat. Liquid forms should be measured carefully. If your dog misses a dose, contact your vet for instructions. In many cases, they will advise giving it when remembered unless it is close to the next dose. Do not double up unless your vet tells you to.

This medication often takes 3 to 4 weeks to start affecting behavior, and 4 to 8 weeks for fuller benefit. If there is no meaningful improvement after about 8 weeks, your vet may reassess the diagnosis, dose, behavior plan, or medication choice.

Do not stop fluoxetine abruptly unless your vet directs you to. Some dogs need a gradual taper, especially after longer-term use.

Many dogs tolerate fluoxetine reasonably well, but side effects do happen. The most common ones are decreased appetite, calmness or lethargy, vomiting, diarrhea, restlessness, and shaking or tremors. Some dogs also pant more, drool, seem disoriented, or act more irritable during the adjustment period.

Mild side effects sometimes improve after the first week or two, especially sleepiness or lower energy. Appetite changes deserve closer attention because some dogs lose noticeable weight. If your dog is eating poorly, losing weight, or acting unlike themselves, update your vet promptly.

More serious concerns include seizures, marked agitation, worsening aggression, incoordination, or signs that could fit serotonin syndrome after an interaction or overdose. See your vet immediately if those happen.

If your dog seems worse rather than better, that does not always mean the medication is wrong. It may mean the dose, diagnosis, timing, or companion behavior plan needs adjustment. Your vet can help sort that out.

Fluoxetine has several important interactions, so your vet should know about every prescription, over-the-counter product, supplement, calming aid, and flea or tick product your dog receives.

The biggest concern is combining fluoxetine with monoamine oxidase inhibitors (MAOIs) such as selegiline or products containing amitraz. These combinations can raise the risk of dangerous serotonin-related reactions. Reconcile labeling also warns against use within 14 days of stopping an MAOI.

Caution is also needed with other serotonin-affecting drugs, some pain medications, trazodone, clomipramine, certain anti-nausea drugs, and medications that may lower the seizure threshold. NSAIDs may increase the risk of GI side effects or bleeding in some patients. Dogs with a seizure history, severe liver disease, diabetes, pregnancy, or lactation may need a different plan or closer monitoring.

Never share human fluoxetine with your dog unless your vet specifically prescribed it. Human strengths and formulations may not match your dog's needs.