Mirtazapine (Remeron®) for Dogs and Cats

A collection of multi-colored pills assorted around a white bottle on a blue table.A collection of multi-colored pills assorted around a white bottle on a blue table.
A collection of multi-colored pills assorted around a white bottle on a blue table.A collection of multi-colored pills assorted around a white bottle on a blue table.

Table of Contents:

  1. How Does Mirtazapine Work for Dogs and Cats?
  2. Brand Names for Mirtazapine
  3. Uses of Mirtazapine for Dogs and Cats
  4. Mirtazapine for Dogs and Cats: Precautions and Side Effects
  5. Dosage Information of Mirtazapine for Dogs and Cats

Mirtazapine, commonly known as Remeron®, Soltab®, Zispin, Avanza, Axit, is used as an appetite stimulant and anti-nausea drug for dogs and cats. Mirtazapine can be used in combination with other anti-vomiting drugs.

Mirtazapine is an orally administered drug belonging belongs to the piperazine-azepine group of drug compounds, commonly referred to as the tetracyclic antidepressants commonly used to treat depression and mood disorders in humans. Other related drugs in this class include tricyclic antidepressants such as desipramine (Norpramin).

How Does Mirtazapine Work for Dogs and Cats?

The exact mechanism of action of mirtazapine is not completely understood. The drug work by raising the levels of neurotransmitters in nerves in the brain that in humans has been shown to help eliminate the sensations of depression such as feelings of sadness and gloom. Increased levels of the neurotransmitters norepinephrine and serotonin are associated with feelings of comfort and relaxation.

Brand Names for Mirtazapine

This drug is registered for use in humans only. Mirtazapine was approved by the FDA in 1996.

  • Human formulations: Remeron®, Soltab®, and various generics. Soltab® is the orally disintegrating tablets.
  • Veterinary formulations: None

Mirtazapine is available as scored film-coated tablets containing 7.5 milligrams, 15 milligrams or 30 milligrams of medication. The oral disintegrating tablets are available as 15, 30, and 45 milligram tablets.

Uses of Mirtazapine for Dogs and Cats


Mirtazapine is used as an anti-nausea drug and/or appetite stimulant in dogs and cats. It is commonly used to treat nausea in cats secondary to chronic kidney disease and in pets with chemotherapy-induced nausea.

Mirtazapine for Dogs and Cats: Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, Mirtazapine can cause side effects in some animals. In cats, side effects may include increased vocalization,  increased affection, muscle twitching, agitation, hyperactivity, and other behavioral changes. The most common side effect in dogs and cats is drowsiness.

In cases of overdose or in select pets sensitive to the effects of serotonin, the drug can cause tremors, agitation, elevated heart rate, elevated body temperature, high blood pressure, difficulty breathing and/or dilated pupils. Cyproheptadine can be used as an antidote. Mirtazapine should not be used in animals with known hypersensitivity or allergy to the drug.

Mirtazapine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with Mirtazapine. Such drugs include tramadol, other anti-anxiety medications such as fluoxetine (Prozac), Diazepam (Valium), lorazepam (Ativan), Clonazepam (Klonopin) or Alprazolam (Zanax). Narcotic drugs, other tricyclic antidepressants, certain antihypertensive mediations (Clonidine, propranolol) and some antihistamine can interact with Mirtazapine.

Dosage Information of Mirtazapine for Dogs and Cats

Medication should never be administered without first consulting your veterinarian.

If your dog is not eating, it is recommended to work with your veterinarian to help determine the underlying cause.

For use in cats as an appetite stimulant, the most common dosing is 3.75 milligrams/dose (¼ of a 15 milligram pill) per cat every 48 to 72 hours (every 2 to 3 days).  A lower dose of 1.88 milligram total dose (1/8 of a 15 milligram tablet) is recommended in cats with kidney failure.

For use in dogs as an appetite stimulant, the most common dosing is 0.6 milligram/kilogram orally every 24 hours, not to exceed 30 milligrams/day. A common dosage reference is:

  • 3.75 milligrams per dog PO every 24 hours for dogs < 11 pounds body weight(¼ of a 15 milligram pill total dose once daily)
  • 7.5 milligrams per dog PO every 24 hours for dogs 11 to 22 pounds body weight(1/2 of a 15 milligram pill total dose once daily)
  • 11.25 milligrams per dog PO every 24 hours for dogs 22 to 33 pounds body weight(3/4 of a 15 milligram pill total dose once daily)
  • 15 milligrams per dog PO every 24 hours for dogs 33 to 66 pounds body weight(one 15 milligram pill total dose once daily)
  • 22.75 milligrams per dog PO every 24 hours for dogs 66 to 110 pounds body weight
  • 30 milligrams per dog PO every 24 hours for dogs over 110 pounds body weight

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed.

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