Fluvoxamine
Fluvoxamine maleate
Also known as: Luvox CR · Dumirox · Faverin · Fevarin · DU-23000 · desifluvoxamin · Dumyrox · Favoxil · Felixsan · Flox-ex · Floxyfral · Fluvohexal · Fluvoxadura · Fluvoxin · Maveral
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| For treatment of compulsive disorders | 0.5-2 mg/kg PO twice daily | PO | q12h | — | 🌎 NA |
| For treatment of behavioral diagnoses | 1-3 mg/kg PO once daily (q24h) | PO | q24h | allow 8 weeks for initial trial | 🌎 NA |
| For treatment of behavioral diagnoses | 1 mg/kg PO q12-24h | PO | q12-24h | Treat for 3-5 weeks minimum to assess effects; then treat until 'well' (minimum another 1-2 months). Continue for another 1-2 months minimum. | 🌎 NA |
- For treatment of behavioral diagnoses: Treatment should last for a minimum 4-6 months once initiating therapy. If weaning off, do so over 3-5 weeks (or longer).
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| For treatment of compulsive disorders | 0.25-0.5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| For treatment of behavioral diagnoses | 0.25-0.5 mg/kg PO q24h | PO | q24h | Treat for 3-5 weeks minimum to assess effects; then treat until 'well' (minimum another 1-2 months). Continue for another 1-2 months minimum. | 🌎 NA |
| For spraying | 0.25 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| For treatment of behavioral diagnoses | 0.5-1 mg/kg PO once daily (q24h) | PO | q24h | allow 8 weeks for initial trial | 🌎 NA |
- For treatment of behavioral diagnoses: Treatment should last for a minimum 4-6 months once initiating therapy. If weaning off, do so over 3-5 weeks (or longer).
- For spraying: Avoid use with benzodiazepines
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Fluvoxamine is a selective serotonin-reuptake inhibitor (SSRI) antidepressant used in veterinary medicine to treat a variety of behavior disorders in dogs and cats, including aggression and stereotypic or obsessive-compulsive behaviors.
While not as commonly prescribed as fluoxetine, it serves as a viable alternative for behavioral management.
Clinical Pearls:
- Like all SSRIs, fluvoxamine requires a prolonged trial period (typically 6-8 weeks) to achieve full clinical efficacy due to the time required for neuroreceptor down-regulation.
- It should not be abruptly discontinued; tapering over 3-5 weeks is recommended to avoid withdrawal signs.
- Anorexia is a common, though usually transient, side effect in dogs that can sometimes be managed by hand-feeding or increasing food palatability.
Mechanism of action
Fluvoxamine acts by highly selective inhibition of the serotonin transporter (SERT) in the central nervous system.
Mechanism: Blockade of presynaptic reuptake → increased concentration of serotonin (5-HT) in the synaptic cleft → prolonged receptor stimulation. Over time, this chronic elevation leads to the down-regulation and desensitization of post-synaptic 5-HT receptors, which correlates with the delayed onset of clinical behavioral improvement. It has minimal to no effect on dopamine or norepinephrine reuptake.
Safety & warnings
Contraindications
- Patients with known hypersensitivity to fluvoxamine or other SSRIs
- Concurrent use of Monoamine Oxidase Inhibitors (MAOIs) such as selegiline or amitraz
- Concurrent use of cisapride
Adverse effects
- Anorexia/decreased appetite (common)
- Lethargy or sedation
- Gastrointestinal upset (vomiting, diarrhea)
- Anxiety, irritability, or agitation
- Insomnia or hyperactivity
- Panting (dogs)
- Changes in elimination patterns (cats)
- Paradoxical aggressive behavior in previously non-aggressive dogs
Precautions
Caution: Use with care in patients with severe cardiac, renal, or hepatic disease. Dosages may need to be reduced in patients with severe renal or hepatic impairment, or in geriatric patients.
- Pregnancy: FDA Category C. Animal studies in rats showed increased pup mortality at birth and decreased birth weights.
- Lactation: Fluvoxamine enters maternal milk, though it appears unlikely to be of significant clinical concern.
Drug interactions
Fluvoxamine may paradoxically decrease the clinical efficacy of buspirone.
Fluvoxamine may increase plasma levels of cisapride, leading to toxicity. Concurrent use is contraindicated.
May decrease or reverse the effects of SSRIs (useful in treating serotonin syndrome).
Fluvoxamine may increase diazepam (and other benzodiazepine) levels.
Fluvoxamine may increase the effects of diltiazem; bradycardia has been reported in humans.
High risk for serotonin syndrome; contraindicated. A 5-week washout is required after stopping fluvoxamine, and a 2-week washout if stopping the MAOI first.
Fluvoxamine may increase plasma levels of methadone, leading to toxicity.
Increased plasma levels of phenytoin possible.
Fluvoxamine may increase these beta-blockers' plasma levels; atenolol may be safer.
Fluvoxamine may increase plasma levels of theophylline.
SSRIs can inhibit the metabolism of tramadol to active metabolites, decreasing efficacy and increasing toxicity risk (serotonin syndrome, seizures).
Fluvoxamine may increase TCA blood levels and increase the risk for serotonin syndrome.
Fluvoxamine may increase the risk for bleeding.
Monitoring
- Clinical efficacy (behavioral improvement)
- Adverse effects, particularly appetite and body weight
- Baseline liver function tests (consider re-testing as needed)
- ECG (consider baseline and re-test as needed)
Pharmacokinetics
Half-life
Absorption
In dogs, fluvoxamine appears to be completely absorbed. In humans, it is absorbed after oral administration with a bioavailability of around 50%. Food does not appear to affect absorption.
Distribution
In humans, it is widely distributed in the body and about 80% bound to plasma proteins.
Metabolism
Extensively metabolized in the liver to non-active metabolites.
Elimination
Eliminated primarily in the urine. In dogs, only about 10% of a dose is excreted unchanged in the urine.
Overdose
Limited data exists for animals. Any dosage over 10 mg/kg can reportedly cause tremors and lethargy.
Clinical Signs of Overdose: Vomiting, somnolence/coma, tremors, diarrhea, hypotension, heart rate/rhythm disturbances (bradycardia/tachycardia, ECG changes), and seizures. Fatalities have been reported in human overdoses.
Treatment:
- Standard protocols for GI decontamination (drug adsorption/removal) for potentially dangerous overdoses.
- Symptomatic and supportive therapy.
- Serotonin Syndrome Management: Cyproheptadine (1.1 mg/kg PO or rectally) may be used as an adjunctive treatment to negate serotonin effects.
- Seizure Control: Diazepam may be used to treat seizures or other severe neurologic signs.
Available products
Formulations
- Oral tablets
- Oral extended-release capsules
Human-labeled
- Fluvoxamine Oral Tablets: 25 mg, 50 mg, & 100 mg (Luvox®, generic)
- Fluvoxamine Oral Extended-release Capsules: 100 mg & 150 mg (Luvox CR®)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Commercially available tablets should be stored in tight containers at room temperatures of 15-30°C (59-86°F) and protected from high humidity.
Client information
- Patience is Key: This medication will not work immediately. It typically requires a commitment of 6 to 8 weeks of continuous use to see significant behavioral improvement.
- Behavioral Training: Fluvoxamine is most effective when combined with a professional behavior modification program.
- Side Effects: Watch for decreased appetite, lethargy, vomiting, or abnormal behavior (such as increased anxiety or aggression). If your pet stops eating entirely, contact your veterinarian.
- Safe Storage: Keep this medication strictly out of reach of children and other pets.
- Do Not Stop Abruptly: If treatment needs to be discontinued, your veterinarian will guide you on how to gradually taper the dose to prevent withdrawal symptoms.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.