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Mirtazapine for Veterinary Use

For Veterinary Practices
Prescribe Now
For Pet & Horse Owners
Manage Your Prescriptions

by Barbara Forney, VMD


Therapeutic Class


May Be Prescribed by Vets for:
Appetite stimulant

FDA Status
No veterinary approved products available.

Search for Available Dosage Forms

Basic Information

Mirtazapine is a human anti-depressant drug that is used as an add-on drug for severe depression. It is particularly useful for patients with anxiety and sleep disturbance. Mirtazapine has a rapid onset of activity in comparison to many anti-depressant medications. It has a dual mechanism of action, being both a noradrenergic and specific serotonergic drug (NaSSA). Mirtazapine is metabolized primarily by the liver.

Dosage Forms


Mirtazapine is used as an appetite stimulant and anti-emetic in cats. At this time there is very little scientific information available on this drug in cats, although it is mentioned in the proceedings of a number of feline veterinary meetings. Anecdotal use includes cats with chronic renal failure, pancreatitis, diabetes mellitus, and other depressed, older, sick-cat situations. Possible advantages for the use of mirtazapine over cyproheptadine is the once every three days dosing and the anti-emetic properties. In human medicine, the notable downside to mirtazapine is weight gain. When treating sick, anorectic cats, this might be considered a positive attribute.

Mirtazapine Side Effects

The most-common side effects in humans are somnolence, dry mouth, increased appetite, and weight gain.


No precautions regarding use of mirtazapine in cats were found in the literature.

Drug Interactions

Based on the human literature, mirtazapine has fewer drug-interactions than many of the other drugs used to treat depression. There is no specific information available regarding treatment in cats.


Mirtazapine has a wide margin of safety in humans. No information was found in the literature regarding cats. If an overdose is recognized promptly, gut-emptying protocols may be attempted.

About the Author

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.

The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease.

Wedgewood Pharmacy compounded veterinary preparations are not intended for use in food and food-producing animals.