Mirtazapine for Dogs and Cats
Vet-reviewed by Dr. Pippa Elliott, BVMS MRCVS ·
What is Mirtazapine for Dogs and Cats
Overview
Mirtazapine is a human antidepressant that veterinarians use off label to help stimulate appetite and reduce nausea in dogs and cats. It works on several receptors in the brain, including serotonin and histamine receptors, which help improve appetite, reduce vomiting, and support overall comfort in sick pets.In pets with chronic diseases like kidney disease or gastrointestinal problems, mirtazapine may help increase food intake, decrease nausea, and support better energy levels. Studies show that dogs receiving mirtazapine tend to eat more, show more interest in food, and gain back weight more easily.Explore more digestive and GI medications in our Digestive section.
What Is Mirtazapine for Dogs and Cats Used For
| Condition | Notes |
|---|---|
| Loss of appetite (anorexia) | Widely used to stimulate appetite in sick pets. |
| Nausea and vomiting | Helps reduce nausea that prevents pets from eating. |
| Chronic kidney disease | Improves appetite in dogs with renal disease. |
| Gastrointestinal disease | Supports dogs experiencing nausea, food aversion, or reduced intake. |
| Post-surgical or illness recovery | Helps pets regain their appetite during recovery. |
| Weight loss in chronic illness | Supports weight gain or prevents further loss. |
How Mirtazapine for Dogs and Cats Works
Mirtazapine works by blocking several serotonin receptors, including 5HT2 and 5HT3, which are involved in nausea and appetite regulation. It also blocks histamine receptors, which can make pets feel calmer and more relaxed. Together, these effects help reduce nausea and increase appetite and interest in food.
Drug Facts
Mirtazapine is an appetite stimulant and anti-nausea medication used off label in dogs and cats. It is commonly given as an oral tablet or compounded liquid. In some formulations, an extended-release version exists for cats, but most veterinary use involves the immediate-release form. It is often used once daily or every other day depending on the pet's condition and sensitivity.
Common Brands
Remeron, Petzipine-15
Drug Class
Antidepressant, appetite stimulant
Substance Classification
Not a controlled substance
Generic Status
Generic widely available
Availability
Prescription required
Mirtazapine for Dogs and Cats Dosage Forms
Mirtazapine is available in oral tablets and compounded liquids for dogs. The oral tablet is the most commonly used form. Many veterinary pharmacies also offer flavored liquid versions for pets that cannot take tablets.
Oral Tablets (30 pcs)
| Qty/Size | Price as low as | Price per unit |
|---|---|---|
| 7.5 mg | $9.00 | $0.30 |
| 15 mg | $12.00 | $0.40 |
| 30 mg | $18.00 | $0.60 |
Oral liquid (4 mg/mL)
| Qty/Size | Price as low as | Price per unit |
|---|---|---|
| 50 mL | $55.00 | $1.10 |
| 100 mL | $95.00 | $0.95 |
Compounded liquid (2 mg/mL)
| Qty/Size | Price as low as | Price per unit |
|---|---|---|
| 30 mL | $30.00 | $1.00 |
| 60 mL | $50.00 | $0.83 |
Typical Dosing For Mirtazapine for Dogs and Cats
Mirtazapine is usually given once daily or every 24 to 48 hours depending on the pet’s size, health condition, and sensitivity. Dogs often respond well to lower doses, and many veterinarians start with the mildest effective amount. Dosing may vary based on nausea severity, appetite level, and underlying disease.
Oral dosing
| Group | Typical Dose | Notes |
|---|---|---|
| Small dogs | 1.1 mg to 3.5 mg once daily | Often starts low to reduce sedation. |
| Medium dogs | 3.75 mg to 7.5 mg once daily | Common clinical range. |
| Large dogs | 7.5 mg to 15 mg once daily | Higher end for severe appetite loss. |
| Dogs with kidney disease | Reduced dose every 48 hours | Prevents drug buildup. |
Risks and Warnings for Mirtazapine for Dogs and Cats
Mirtazapine is typically well tolerated, but some dogs may experience side effects. The most common include sedation, vocalization, restlessness, or increased affection. Some dogs may also show drooling, increased heart rate, or mild agitation, especially at higher doses.
Pets with liver disease or kidney disease may metabolize the drug more slowly, requiring reduced or less frequent dosing. Overdose can lead to tremors, rapid heart rate, and agitation, and requires immediate veterinary care.
Mirtazapine for Dogs and Cats Warnings and Precautions
Use mirtazapine with caution and under veterinary guidance.
- Avoid use with monoamine oxidase inhibitors such as selegiline or amitraz.
- Use cautiously in dogs with liver or kidney disease.
- Monitor for excessive sedation or agitation.
- Do not give more often than prescribed.
- Store securely to prevent accidental ingestion.
Disclaimer: This information is for educational purposes only and should not replace professional veterinary advice. Always consult your veterinarian before using or combining any medications for your pet.
Frequently Asked Questions (FAQ)
How long does mirtazapine take to work?
Most dogs show improved appetite within a few hours of receiving the medication.
Can mirtazapine be given with food?
Yes. Mirtazapine can be given with or without food.
Is mirtazapine safe for long-term use?
It may be used long term under veterinary supervision, especially for chronic conditions like kidney disease.
What if my dog becomes too sedated?
Contact your veterinarian. A lower dose or different dosing schedule may solve the problem.
Can mirtazapine be used in cats?
Yes, but dosing and formulations for cats are different. Only give cat-specific dosing if your veterinarian prescribes it.
Related Medications & Supplements
Dogs experiencing nausea, vomiting, or reduced appetite may need additional gastrointestinal support. These related medications are commonly used alongside appetite stimulants like mirtazapine to help manage stomach upset, nausea, and digestive discomfort.
- Maropitant - anti-nausea medication used to control vomiting
- Ondansetron - antiemetic that helps reduce nausea
- Metoclopramide - medication that supports gut motility and reduces vomiting
- Omeprazole - acid-reducing drug used for stomach and upper GI irritation
- Famotidine - antacid that helps reduce gastric acid and soothe the stomach
References
- Theodoro, S., et al. (2025) ‘Evaluation of the Short-Term Effects of Mirtazapine on Appetite Stimulants in Dogs: A Retrospective Study and a Placebo-Controlled Trial’, Animals (Basel)., 15(17), 2538. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12427372/
- Arguelles, J., et al. (2023) 'Use of mirtazapine in the treatment of canine behaviour problems: A review of 32 cases’, VetRecord, 194(8), e3670. Available at: https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/vetr.3670
- Zalischi, D.B., Popescu, C., Ionescu, R., & Constantinescu, A. (2023) ‘Mirtazapine in veterinary medicine: focus on its role in gastrointestinal disorders - review’, Romanian Journal of Veterinary Science, 56, pp. 215-223. Available at: https://rjvs.ro/admin/articole/904981744720_72438_Zalischi_DB.pdf
- Carvalho, S., et al. (2025) ‘Owner’s Perspective About the Use of Mirtazapine Transdermal Ointment in Cats—A Survey-Based Study’, Animals, 15(20), 3054. Available at: https://www.mdpi.com/2076-2615/15/20/3054
- Richter, C., et al. (2023) ‘The use of mirtazapine as an adjunct agent to fluoxetine and paroxetine in the treatment of canine fear-, anxiety-, and aggression-based disorders: A retrospective study of 71 cases’, Journal of Veterinary Behavior, 71, pp. 9-17. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1558787823001442
- Quimby, J.M., et al. (2019) ‘Assessment of compounded transdermal mirtazapine as an appetite stimulant in cats with chronic kidney disease’, Journal of Feline Medicine and Surgery. Available at: https://journals.sagepub.com/doi/full/10.1177/1098612X19851303
Editor
The Webvet Editorial Team is a collective of seasoned pet-care journalists, veterinary content specialists, and industry editors dedicated to delivering accurate, trustworthy, and compassionate pet health information. With decades of combined experience across veterinary reporting, pet wellness education, and consumer product research, our team works closely with veterinarians and certified pet experts to ensure every article is both evidence-based and easy to understand.
Veterinarian · BVMS MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty Puggle named Poggle, 3 cats and a bearded dragon.
