Stomach & digestion Dogs & Cats

Ondansetron (Zofran) for dogs and cats

Treats severe nausea and vomiting. [1]

Last reviewed: October 2026 · 2 sources · see sources

Quick answerOndansetron is a prescription medicine for dogs and cats. It blocks serotonin signals that trigger vomiting. The most common side effects: rare: constipation, sleepiness, head shaking.

Key facts

Generic nameOndansetron
Common brand namesZofran
Used inDogs & Cats
TypeStomach & digestion
Prescription?Prescription
Typical US priceNot listed (no reliable public source)

What it's used for

Treats severe nausea and vomiting. [1]

How it works

It blocks serotonin signals that trigger vomiting. [1]

Side effects and cautions

Common side effects: Rare: constipation, sleepiness, head shaking. [1]

Use with care: Use caution with gut blockage, certain heart rhythm problems or MDR1-sensitive breeds. [1]

Call your vet right away if your pet has trouble breathing, facial swelling, hives, collapse, or any side effect that is severe or getting worse.

About dosingDosing is your vet's call. We don't list doses because the right amount depends on your pet's weight, age, health and other medicines. Don't change a dose or stop a medicine without asking your vet, and never give a pet medicine meant for people unless your vet tells you to [2].

What it costs

We don't list a price for this one because we couldn't find a reliable public source. Ask your vet or pharmacy for a quote; prices depend on your pet's size, the dose and where you fill it.

Ondansetron FAQ

What is Ondansetron used for in dogs and cats?

Treats severe nausea and vomiting.

What are the side effects of Ondansetron?

Rare: constipation, sleepiness, head shaking.

Does Ondansetron need a prescription?

Yes. It needs a prescription from a veterinarian.

How much Ondansetron should I give my pet?

Only your veterinarian can tell you. The right dose depends on your pet's weight, health and other medicines, so we don't list doses. Never give a pet a medicine prescribed for a person or another animal without asking your vet.

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This page is general information for pet owners, not veterinary advice. Talk to your vet about your own pet.

Sources (2) — tap to show
  1. VCA Animal Hospitals – Ondansetron (veterinary drug handout)
  2. FDA – Frequently asked questions about animal drugs