Appetite stimulant / Tetracyclic antidepressant · For Cats

Mirataz dosage reference for cats (Mirtazapine)

This page's standard weight-based reference is 0.5 mg per kg (0.23 mg per lb), with every 48-72 hours (oral) or daily (transdermal Mirataz) recorded as the reference frequency. Use the calculator to see the arithmetic for your cat's weight, then confirm the indication, product, and actual dose with a veterinarian.

Onset: 1-2 hours
Duration: 48-72 hours in cats
Class: Appetite stimulant / Tetracyclic antidepressant

Weight-based calculator estimate from the references listed on this page. This page has not been independently DVM-reviewed — see our methodology .

This information is for educational purposes only. Always consult your veterinarian before giving medication to your pet. Do not use this calculator for emergencies, overdoses, pregnancy, very young animals, very old animals, pets with liver/kidney disease, or pets taking multiple medications.

Each medication page lists the references recorded for its data. The calculator math and editorial presentation are maintained by PetDosageChart; a page is independently DVM-reviewed only when a named reviewer byline appears. See our methodology and limitations.

Mirtazapine (often known by brand names such as Mirataz and Remeron) is an appetite stimulant / tetracyclic antidepressant commonly used in veterinary medicine for appetite stimulation, weight loss in chronic kidney disease, nausea reduction, and appetite loss from cancer or chemotherapy. Understanding the correct dosage, administration, and potential side effects of Mirtazapine is critical for your cat’s safety and well-being.

A typical Mirtazapine dose for cats is around 0.5 mg/kg every 48-72 hours (oral) or daily (transdermal Mirataz), within a usual range of 0.4-0.75 mg/kg. Available forms include tablet and transdermal ointment.

Calculator Warning: Use this only as an educational estimate. Your veterinarian may prescribe a different dose based on your pet’s condition, age, weight, other medications, and medical history.

Mirtazapine Dosage Calculator for Cats

Enter your cat’s weight below to estimate the Mirtazapine dose from the 0.5 mg/kg guideline. Your veterinarian may adjust it for your cat’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.

Dosage Calculator · 01

Enter your cat's weight

Quick Dosage Chart

Typical Mirtazapine amounts for common cat weights, for quick reference:

Dosage Chart · 02

Mirataz weight-based reference chart for cats

Scroll sideways to see full table

Weight	Lower Reference	Standard Reference	Upper Reference	Frequency
3 lbs (1.4 kg)	0.56 mg	0.70 mg	1.0 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
4 lbs (1.8 kg)	0.72 mg	0.90 mg	1.4 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
5 lbs (2.3 kg)	0.92 mg	1.1 mg	1.7 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
6 lbs (2.7 kg)	1.1 mg	1.4 mg	2.0 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
7 lbs (3.2 kg)	1.3 mg	1.6 mg	2.4 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
8 lbs (3.6 kg)	1.4 mg	1.8 mg	2.7 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
9 lbs (4.1 kg)	1.6 mg	2.0 mg	3.1 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
10 lbs (4.5 kg)	1.8 mg	2.3 mg	3.4 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
12 lbs (5.4 kg)	2.2 mg	2.7 mg	4.1 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
14 lbs (6.3 kg)	2.5 mg	3.1 mg	4.7 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
16 lbs (7.3 kg)	2.9 mg	3.6 mg	5.5 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
18 lbs (8.2 kg)	3.3 mg	4.1 mg	6.1 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
20 lbs (9.1 kg)	3.6 mg	4.5 mg	6.8 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)
25 lbs (11.3 kg)	4.5 mg	5.7 mg	8.5 mg	every 48-72 hours (oral) or daily (transdermal Mirataz)

Parenthetical tablet amounts are arithmetic comparisons only. They do not account for scoring, release type, concentration, product labeling, or whether this medication is appropriate for an individual animal.

By Weight

Mirataz reference by cat weight

Choose a common weight to open its optional reference page. Use the main medication calculator for a different exact weight.

Common-weight pages are convenience views of the same educational reference, not separate medical recommendations.

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How to Give Mirtazapine to Your Cat

Cats metabolize mirtazapine much more slowly than dogs or humans, so dosing must be every 48-72 hours for oral tablets — never daily. A typical oral dose is 1/8 to 1/4 of a 15 mg tablet (1.88-3.75 mg). The FDA-approved transdermal ointment (Mirataz) is applied to the inner ear flap daily with a gloved finger — rotate ears and wipe the old dose off before applying a new one. For oral tablets, you can hide them in a pill pocket or give directly using a pill gun.

It may interact with SSRIs (fluoxetine), tramadol, cyproheptadine, and MAO inhibitors.

Side Effects and Safety

Common side effects include vocalization, restlessness, increased affection or kneading, and mild sedation. More serious side effects can occur, such as serotonin syndrome (tremors, agitation, high heart rate), severe sedation, liver toxicity with overdose, and abnormal heart rhythms.

Cautions · 12

When Mirataz should be used with caution or avoided

Some cats should not take Mirataz, or need a different dose and closer monitoring. Tell your veterinarian about your pet's full health history and every other medication or supplement they take before giving Mirataz.

concurrent use with other serotonergic drugs
severe liver disease
known hypersensitivity
pregnancy

Interactions · 13

Mirataz drug interactions

Mirataz can interact with other drugs. This list is not complete — always give your veterinarian a full list of your cat's medications and supplements.

SSRIs (fluoxetine)

tramadol

cyproheptadine

MAO inhibitors

Calculator Limits · 14

When not to use this calculator

This calculator gives a general educational estimate for a healthy adult cat at a known weight. Do not rely on it in these situations — talk to your veterinarian instead:

In an emergency, or after accidental ingestion or a suspected overdose
For pregnant or nursing pets
For very young or very old cats
For pets with liver disease, kidney disease, or another chronic illness
For pets taking several medications at once
When you are not sure of your cat's current, accurate weight
For combination products that contain additional active ingredients

Overdose · 15

Suspected overdose: what to do

If you think your cat had too much Mirataz, or swallowed any medication by accident, act right away. Do not wait for symptoms to appear.

Call your veterinarian or the nearest emergency animal hospital.
ASPCA Animal Poison Control Center: (888) 426-4435
Pet Poison Helpline: (855) 764-7661

A consultation fee may apply to the poison hotlines. Have the medication packaging ready, and note how much your pet may have taken and when. Do not try to make your pet vomit unless a veterinarian tells you to.

When to Call the Vet

If your cat experiences any of the following, contact your veterinarian or an emergency clinic immediately:

Tremors, twitching, or agitation (signs of serotonin syndrome)
Extreme sedation or inability to stand
Rapid or irregular heartbeat
Vomiting that does not stop after 24 hours
Yellowing of gums or skin (jaundice)

Frequently Asked Questions

Frequently Asked · 07

Questions about this medication

Why can cats only get mirtazapine every other day?

Cats metabolize mirtazapine significantly slower than humans or dogs. The half-life in cats is approximately 15-20 hours, compared to about 2-4 hours in dogs. Giving it daily orally can lead to drug accumulation and toxicity, including serotonin syndrome. The transdermal formulation (Mirataz) is specifically dosed for daily application in cats.

How quickly does mirtazapine make a cat want to eat?

Most cats show increased interest in food within 1-2 hours of administration. The appetite-stimulating effect typically peaks within a few hours and can last 48-72 hours. Offer your cat their favorite food shortly after giving the medication for best results.

Is mirtazapine safe for cats with kidney disease?

Yes, mirtazapine is commonly and safely used in cats with chronic kidney disease (CKD) to combat appetite loss and weight loss. However, because CKD can slow drug metabolism further, your vet may recommend a lower dose or longer interval between doses. The transdermal form (Mirataz) is FDA-approved specifically for weight loss in cats.

Can I use human mirtazapine for my cat?

Human mirtazapine tablets (typically 15 mg) can be used but must be carefully dosed — cats need only 1/8 to 1/4 of a tablet. The FDA-approved transdermal ointment Mirataz is specifically formulated for cats and is easier to dose accurately. Never give a whole human tablet to a cat.

What are signs of mirtazapine overdose in cats?

Signs of overdose include agitation, vocalization, tremors, rapid heart rate, disorientation, and seizures — collectively known as serotonin syndrome. If you suspect an overdose, contact your veterinarian or an animal poison control hotline immediately. Due to the long half-life in cats, symptoms can persist for 24+ hours.

Use This Guide Safely · 08

What weight alone cannot tell you

The calculator performs one narrow job: it multiplies your cat's weight by the lower, standard, and upper mg/kg values recorded for Mirataz. It cannot decide whether this drug, indication, formulation, or schedule is appropriate for an individual animal.

Context in this medication record

Commonly listed uses: appetite stimulation, weight loss in chronic kidney disease, nausea reduction, appetite loss from cancer or chemotherapy
Recorded forms: tablet, transdermal ointment
Reference timing: every 48-72 hours (oral) or daily (transdermal Mirataz); onset 1-2 hours; duration 48-72 hours in cats

Individual checks a calculator cannot perform

Confirm the diagnosis and the reason this medication is being considered.
Match the exact product, concentration, route, and whether a tablet may be split.
Account for age, pregnancy, organ function, genetics, allergies, and prior reactions.
Review every prescription, over-the-counter product, and supplement your pet takes.

Recorded cautions

concurrent use with other serotonergic drugs; severe liver disease; known hypersensitivity; pregnancy.

Recorded interactions

SSRIs (fluoxetine); tramadol; cyproheptadine; MAO inhibitors.

These lists reproduce the structured record used by this page and may not be exhaustive. Show your veterinarian the product label and your cat's complete medication list before acting on a number.

Related · 08

Related medications for cats

Sources · 09

Sources & references

The structured medication record behind this page names the references below. The links open the publisher or official resource; they do not turn this page into a prescription for an individual animal.

Plumb's Veterinary Drug Handbook — listed in this medication's source record.
Merck Veterinary Manual — listed in this medication's source record.
DailyMed label search for Mirtazapine — check current product and formulation labels; some veterinary uses may be off-label.

Source names are shown at the record level; passage-level page and label citations are still being added. Read our methodology and limitations.

Transparency · 11

How this page was made

This page's structured medication record includes Plumb's Veterinary Drug Handbook among its source names. PetDosageChart applies the record's mg/kg values to the entered weight and presents the arithmetic result. A source record is not the same as an individualized prescription or an independent clinical review.

Sources cited: Plumb's Veterinary Drug Handbook
Merck Veterinary Manual
Calculator formula: Doses scale linearly from a standard basis of 0.5 mg per kg (0.23 mg per lb) of body weight, given every 48-72 hours (oral) or daily (transdermal Mirataz). The calculator multiplies that basis by your cat's weight and shows an arithmetic comparison with recorded tablet sizes. That comparison does not determine whether a tablet is scored, splittable, or appropriate for your pet.
Editorial owner: Prepared and maintained by the PetDosageChart editorial team, a software-led publisher and not a veterinary practice.
DVM review status: Not independently DVM-reviewed. A named reviewer and review date appear here only after a confirmed review.

More on our methodology and editorial process — how we source, calculate, and review cats dosage data.

Safety · 10

More resources

Pet Medication Safety Hub — What's safe, what's dangerous, and emergency signs
How we calculate dosages — Our sources, math, and review process
Printable emergency checklist — One-page reference for your fridge or first aid kit