By Dr. Michelle Frye, DVM · Published 2026-05-01
TL;DR. Mirtazapine is a tetracyclic antidepressant used as a powerful appetite stimulant and antiemetic, primarily for cats. Mirataz is the FDA-approved transdermal ear ointment — 1.5-inch ribbon to the inner ear, once daily, alternating ears. Wear gloves. Onset within hours.
The Cat Who Won't Eat
The 16-year-old cat with chronic kidney disease has decided food is not his thing this week. He drank a little water this morning. He looked at his bowl and walked away. By tomorrow he'll be in early hepatic lipidosis if we don't intervene. This is the situation Mirataz was made for, and it's why every feline practitioner I know keeps a tube on the shelf.
What Mirtazapine Actually Does
Mirtazapine was developed as a human antidepressant. In cats and dogs, the antidepressant effect isn't really the point — it's the appetite-stimulating, antiemetic, and pro-motility side effects that make it indispensable in geriatric and CKD feline practice.
- Mirataz (transdermal): 1.5-inch ribbon (~2 mg) applied to the inner ear, once daily.
- Generic mirtazapine tablets: 1.88 mg per cat every 24–48 hours.
- Onset: hours. Many cats start eating the same day.
- Wear gloves to apply the transdermal — mirtazapine absorbs through human skin too.
- Alternate ears daily to avoid local skin irritation.
Things People Are Wrong About
Myth 1: "More ointment = more effect." No. The 1.5-inch ribbon is calibrated. Doubling can produce hyperactivity, vocalization, and serotonin-related effects.
Myth 2: "I can dose it twice a day." Mirataz is once daily. More frequent dosing increases side effects without improving appetite stimulation.
Myth 3: "It's the same as Cerenia for nausea." Different drug class, different mechanism. Mirtazapine has antiemetic effects but is primarily an appetite stimulant. Cerenia (maropitant) is a selective antiemetic. Many cats benefit from both.
Myth 4: "My cat became hyper, so it's not working." Mild hyperactivity, vocalization, and increased grooming after a dose are normal expected effects of the drug class. They usually fade as the dose-response stabilizes.
When NOT to Use Mirtazapine
Reduce the dose in significant kidney or liver disease (which is most of the patient population it's used in — talk to your vet about appropriate dosing). Avoid combining with other serotonergic drugs (tramadol, fluoxetine, trazodone) without veterinary direction; serotonin syndrome is rare but real. Wash hands after applying the transdermal and keep the cat away from people for 30 minutes — especially children and pregnant women.
What I Tell Owners After 30 Years
Mirataz is one of those rare drugs that has changed how I practice geriatric feline medicine. Before transdermal mirtazapine, getting an inappetent CKD cat to eat reliably required pilling a sick cat every day — a recipe for stress, refusal, and esophageal trauma. The ear ointment changed that. The cat doesn't even know they got the medication. They just notice they're hungry. Use it correctly: gloves on, 1.5-inch ribbon, alternate ears, once a day. Watch the cat eat.
Frequently Asked Questions
How does Mirataz work?
Mirataz is transdermal mirtazapine, an antidepressant whose side effects in cats include powerful appetite stimulation, antinausea action, and mild sedation. It is applied to the inner ear flap and absorbs through the skin.
How much Mirataz do I give my cat?
The labeled dose is a 1.5-inch ribbon (approximately 2 mg) applied to the inner pinna of the ear once daily, alternating ears each day.
How long does Mirataz take to work?
Many cats begin eating within hours of the first dose. Full effect is usually seen by day 2–3.
What are the side effects of mirtazapine in cats?
Vocalization, hyperactivity, agitation, increased grooming, and ear redness are most common. Reduce the dose if any are excessive. Rare effects include serotonin syndrome when combined with other serotonergic drugs.
Can dogs take mirtazapine?
Yes. Dogs occasionally receive mirtazapine for inappetence and nausea, particularly when first-line drugs (Cerenia, Entyce) are insufficient. Dosing differs from cats.
Should I wear gloves to apply Mirataz?
Yes. Mirtazapine is absorbed through human skin and can affect the person applying it. Wear gloves and wash hands afterward.
Can Mirataz be used with Cerenia?
Yes. The two work through different mechanisms and are commonly combined for inappetent, nauseous cats.
Where can I buy Mirataz?
Mirataz is prescription-only. Smarty Vets dispenses Mirataz transdermal, generic mirtazapine, and pharmacy-compounded mirtazapine from a licensed pharmacy.
This article is for educational purposes and is not a substitute for veterinary advice. Always consult your veterinarian before starting, stopping, or changing any medication for your pet.