July 28, 2026 - Ondansetron is a prescription medication veterinarians use to treat nausea and vomiting in dogs and cats.

May 4, 2026 - Though uncommon, possible side effects of ondansetron in cats are: ... Low blood pressure does not have symptoms, but the cat might get lightheaded, feel dizzy, faint, collapse, or be lethargic.

Ondansetron (brand names Zofran®, Zuplenz®) is an antiemetic used off label (extra label) to treat severe nausea and vomiting in dogs and cats.

Side effects are uncommon but may include constipation, sleepiness, or head shaking; rare serious reactions include abnormal heart rhythms, fainting/collapse, or low blood pressure.

While it can be beneficial, there are potential side effects to consider before administering it to your cat. Possible side effects include changes in behavior such as agitation or changes in mood. Ondansetron is generally well-tolerated, but some cats may experience constipation or diarrhea.

August 4, 2026 - Ondansetron appears to be a very well tolerated medication in cats. GI side effects like constipation and diarrhea may rarely occur. While sedation may not be expected, 5-HT3 is a form of serotonin, making sedation possible.

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March 16, 2021 - Veterinarian's Assistant: What’s the cat’s name? Customer: Buddy. Veterinarian's Assistant: Is there anything else the vet should know about Buddy? Customer: We give him subcutaneous fluids every day, along with aluminum hydroxide, maropitant (I know I’m spelling things wrong), and potassium alongside the ondansetron. He has been responding very negatively just to the ondansetron and maropitant (which we now administer through

August 2, 2026 - Ondansetron is a selective 5-HT3 (serotonin) receptor antagonist used off-label in dogs and cats when serotonin-mediated emesis dominates — chemotherapy-induced nausea and vomiting (CINV) and the mucosal injury of parvoviral enteritis — or when vomiting persists despite maropitant. Its short elimination half-life demands frequent dosing (typically q8–12h), and its very low oral bioavailability in dogs is the single most important caveat: a dog swallowing a tablet may achieve negligible plasma concentrations [1]. Treat it as a second antiemetic layered onto maropitant for refractory vomiting rather than a stand-alone first-line agent for routine acute vomiting, where labeled maropitant remains the default.

July 5, 2026 - By blocking these receptors, ondansetron effectively "mutes" the distress signals sent to the brain’s emetic center. This pharmaceutical intervention is often the difference between a cat that refuses to eat and one that maintains its nutritional status.

December 26, 2025 - 2025 Vet Guide Summary: Ondansetron for Dogs & Cats – Use, Dosage, Safety & Side Effects 🐾 Ondansetron (Zofran®) is an effective anti-nausea medication used in veterinary care to treat vomiting in dogs and cats. Dr. Duncan Houston BVSc explains its uses, dosage recommendations, potential side effects, and how it compares to other treatments like Maropitant (Cerenia®). Tools like Ask A Vet, Woopf 🐾, and Purrz 🐶 help ensure safe and effective administration for your pet's comfort.

August 4, 2024 - A lot of naysayers in these comments. Yes, ondansetron is safe for cats and yes it treats nausea. It can be given in conjunction with cerenia and in some cases, it works better. The downside is that the half life in cats is around 6 hours, so it needs to be given several times a day.

July 10, 2024 - Potassium is an important electrolyte that serves many functions in the body, but especially for nerves, muscles, and the heart. Cats with very low or high potassium can develop effects on nerve, muscle, and heart function. Cats obtain potassium through their diet.

August 20, 2021 - Ondansetron is prescribed to treat or prevent severe vomiting. It is especially helpful against nausea and vomiting caused by medications. What problems could my dog or cat have with Ondansetron?

February 26, 2025 - Ondansetron is a common medication that can be used to treat vomiting in dogs and cats. Read this article to learn more about dosage and side effects.

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•Severe lack of energy, fainting, or collapse. Although rare, these could be signs of heart rhythm abnormalities or low blood pressure.

Ondansetron is a 5-HT3 receptor antagonist that is an effective anti-emetic in cats. The purpose of this study was to evaluate the pharmacokinetics of ondansetron in healthy cats. Six cats with normal complete blood count, serum biochemistry, and ...

Ondansetron is an anti-nausea medication that can be safely prescribed for cats under veterinary supervision. Dosage can vary based on your cat's weight, health status, and specific needs, so it is vital to have a vet's input before administering this medication.