Ondansetron for Dogs: Treat and Prevent Nausea and Vomiting
Key takeaways:
Ondansetron (Zofran) is a medication that prevents and treats nausea and vomiting in dogs.
Veterinarians may prescribe ondansetron to treat nausea and vomiting triggered by conditions such as infections, chemotherapy, or vestibular disorders.
Ondansetron’s side effects may include diarrhea, constipation, and sedation. Dogs don’t usually have side effects from this medication, however.
Table of contents
Ondansetron (Zofran) is a commonly prescribed medication that prevents or manages nausea and vomiting in people undergoing cancer treatment. Veterinarians also prescribe ondansetron to treat nausea and vomiting in dogs.
Here’s a look at ondansetron uses in dogs, along with side effects and serious risks.
Ondansetron for dogs at a glance
Common names | Ondansetron (Zofran) |
What it treats | Nausea, vomiting |
How it comes (forms) | Tablets, oral disintegrating tablets, oral solution, injection |
Common side effects | Constipation, diarrhea, mild sedation |
Average cost | $15 to $21 (10 tablets) |
What is ondansetron for dogs, and how does it work?
Ondansetron is a medication used to treat nausea and vomiting in dogs. It works by blocking substances and signals to the brain that cause nausea.
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Zofran is the most common brand name for ondansetron.
What is ondansetron used for in dogs?
Ondansetron is used to treat nausea and vomiting in dogs that may be triggered by certain situations, such as:
Foods that make them sick
Viral or bacterial infections
Medication use
Chemotherapy
Ondansetron may also be used to prevent nausea or vomiting in dogs. It can be given before they take another medication or undergo a procedure.
Vets consider maropitant (Cerenia) to be as effective or better than ondansetron for the prevention of vomiting in dogs. But many veterinarians consider ondansetron more effective for treating nausea.
What is the dosage of ondansetron for dogs, and how is it given?
There is no FDA-approved dosage of ondansetron for dogs. Vets prescribe ondansetron off-label, which is common in veterinary medicine.
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A veterinarian can determine the ondansetron dosage based on your dog’s symptoms. They may adjust the dose depending on how your dog responds to it.
Vets may use an injectable form of ondansetron if your dog is being treated in the hospital for nausea or vomiting.
You may give your dog the oral form of ondansetron every 8 to 12 hours at home. The oral tablet form is most common. Dogs that may not be able to swallow or keep down medication may be able to take the dissolvable tablet.
Ondansetron works fast in dogs. Your dog should start feeling better within 1 to 2 hours.
What are the common side effects of ondansetron in dogs?
Some dogs may experience mild side effects while taking ondansetron. Common side effects in dogs may include:
Mild sedation (sleepiness)
What are the most serious risks of ondansetron in dogs?
Serious side effects of ondansetron have been reported in humans. Your dog may experience these as well, but they’re rare. These include:
Head shaking
Abnormal heartbeat
Low blood pressure
Call a vet right away if your dog shows any of these signs.
Does ondansetron interact with any other dog medications?
The following medications may interact with ondansetron. But this doesn’t mean your dog can’t take ondansetron with it.
Apomorphine
Azole antifungals
Cyclophosphamide
Metformin
Monoamine oxidase inhibitors (MAOIs)
Opioids, such as fentanyl and methadone
Always discuss your dog’s medications with a vet.
What should you do if your dog misses a dose of ondansetron?
Ondansetron is typically given every 8 to 12 hours. If you miss giving your dog a dose of ondansetron, give it as soon as possible. If it’s close to the time for the next dose, wait until the next scheduled dose to give them the medication.
The bottom line
Ondansetron (Zofran) is a medication used to prevent and treat nausea and vomiting in dogs. Side effects like diarrhea and constipation are possible, but they’re typically mild and uncommon.
Ondansetron can interact with other medications your dog takes. Make sure to discuss your dog’s over-the-counter and prescription medications with a vet.
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References
Budde, J. A., et al. (2023). Ondansetron. Plumb’s Veterinary Drug Handbook, 10th Edition. Wiley-Blackwell.
Burke, J. E., et al. (2022). Effectiveness of orally administered maropitant and ondansetron in preventing preoperative emesis and nausea in healthy dogs premedicated with a combination of hydromorphone, acepromazine, and glycopyrrolate. Journal of the American Veterinary Medical Association.
Henze, L., et al. (2022). Ondansetron in dogs with nausea associated with vestibular disease: A double-blinded, randomized placebo-controlled crossover study. Journal of Veterinary Internal Medicine.
Sotelo, C. K., et al. (2022). Pharmacokinetics and anti-nausea effects of intravenous ondansetron in hospitalized dogs exhibiting clinical signs of nausea. Journal of Veterinary Pharmacology and Therapeutics.
Zersen, K. M., et al. (2024). Plasma concentrations of oral ondansetron in hospitalized dogs exhibiting clinical signs of nausea. Veterinary Sciences.
