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Mirtazapine

Prescription

Noradrenergic/Serotonergic Antidepressant / Appetite Stimulant

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

2 available

Interactions

3 documented

Formulations

Mechanism of action

Antagonizes central alpha-2 adrenergic autoreceptors (increasing norepinephrine/serotonin release), blocks 5-HT2 and 5-HT3 serotonin receptors (antiemetic, anxiolytic), and has potent H1-antihistamine activity (appetite stimulation and sedation).

At a glance

Class

Noradrenergic/Serotonergic Antidepressant / Appetite Stimulant

Schedule

Prescription

Storage

Tablets at room temperature; Mirataz ointment at room temperature, use within 28 days after opening

Dosing

🐕

Dog

Used for appetite stimulation, antiemetic, and antinausea properties

Dose

1.88–3.75 mg/dog

Route

Frequency

q24h

🐈

Cat

FDA-approved transdermal formulation (Mirataz) for feline weight loss management

Dose

1.88–3.75 mg/cat

Route

PO, Transdermal

Frequency

q48–72h (PO) or q24h (transdermal)

Educational reference only

This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Other — 3

Strength

—

Strength

—

Strength

—

Storage

Tablets at room temperature; Mirataz ointment at room temperature, use within 28 days after opening

Safety

Monitoring parameters

Body weight (weekly)Food intakeSedation levelApplication site (transdermal)

Educational reference only

Interactions

Major — 2

Fluoxetine

major

Both serotonergic. Fluoxetine inhibits CYP2D6 metabolism of mirtazapine, increasing levels. Serotonin syndrome risk from combined serotonergic activity.

Management: Avoid combination. If appetite stimulation needed with SSRI, reduce mirtazapine dose and monitor for serotonin syndrome.

Selegiline (L-Deprenyl)

major

Mirtazapine (increases serotonin/norepinephrine release) + MAO inhibitor: serotonin syndrome risk.

Management: Avoid. Allow 2-week washout of selegiline before mirtazapine.

Moderate — 1

Tramadol

moderate

Both serotonergic. Additive serotonin effect.

Management: Use with caution. Monitor for serotonin syndrome signs.

Educational reference only

Brands

Other markets

Remeron

Mirataz (transdermal feline)

FAQs

Frequently asked questions

›What is Mirtazapine?

Mirtazapine is a noradrenergic/serotonergic antidepressant / appetite stimulant used in pets. Antagonizes central alpha-2 adrenergic autoreceptors (increasing norepinephrine/serotonin release), blocks 5-HT2 and 5-HT3 serotonin receptors (antiemetic, anxiolytic), and has potent H1-antihistamine activity (appetite stimulation and sedation).

›What is Mirtazapine used for in pets?

Mirtazapine is used in veterinary medicine for: Used for appetite stimulation, antiemetic, and antinausea properties; FDA-approved transdermal formulation (Mirataz) for feline weight loss management.

›What is the Mirtazapine dose for dogs?

For dogs, Mirtazapine is typically dosed as follows — Used for appetite stimulation, antiemetic, and antinausea properties: 1.88–3.75 mg/dog PO q24h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Mirtazapine dose for cats?

For cats, Mirtazapine is typically dosed as follows — FDA-approved transdermal formulation (Mirataz) for feline weight loss management: 1.88–3.75 mg/cat PO/Transdermal q48–72h (PO) or q24h (transdermal). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›Does Mirtazapine need a prescription?

Yes. Mirtazapine is a prescription medication and should only be administered under veterinary supervision.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database