Ondansetron Is a Prescription Anti-Nausea Medication Used to Prevent Nausea and Vomiting From Chemotherapy, Surgery, and Other Causes

If your doctor has prescribed Ondansetron — or you've heard of it by the brand name Zofran — you probably have questions. What does it do? How do you take it? What should you watch out for? This guide covers everything you need to know about Ondansetron in 2026, written in plain language.

What Is Ondansetron?

Ondansetron is a prescription medication that prevents nausea and vomiting. It belongs to a drug class called 5-HT3 receptor antagonists, which work by blocking serotonin signals that trigger the vomiting reflex.

Here are the key facts:

• Brand names: Zofran, Zofran ODT, Zuplenz
• Generic name: Ondansetron (Ondansetron Hydrochloride)
• Drug class: 5-HT3 receptor antagonist (antiemetic)
• Original manufacturer: GlaxoSmithKline (Zofran)
• Generic manufacturers: Teva, Mylan, Aurobindo, Dr. Reddy's, Sandoz, and others
• Controlled substance: No — Ondansetron is not a controlled substance and has no DEA schedule
• Generic available: Yes — generic Ondansetron has been available for years and is significantly cheaper than brand-name Zofran

What Is Ondansetron Used For?

Ondansetron is FDA-approved for three main uses:

1. Chemotherapy-induced nausea and vomiting (CINV) — Taken before and during cancer treatment to prevent nausea from emetogenic chemotherapy
2. Radiation-induced nausea and vomiting — Used in patients receiving radiation therapy
3. Post-operative nausea and vomiting (PONV) — Given before or after surgery to prevent nausea from anesthesia

Doctors also commonly prescribe Ondansetron off-label for:

• Morning sickness and hyperemesis gravidarum (severe pregnancy nausea)
• Stomach flu (gastroenteritis)
• Cyclic vomiting syndrome
• Nausea from other medications
• Itching related to cholestasis or opioid use (emerging use)

How Is Ondansetron Taken?

Ondansetron comes in several forms to fit different needs:

• Oral tablets (4 mg, 8 mg, 24 mg) — Swallow whole with water. Can be taken with or without food.
• Orally disintegrating tablets (ODT) (4 mg, 8 mg) — Place on your tongue and let it dissolve. No water needed. Good option if swallowing pills is difficult or you're actively nauseated.
• Oral solution (4 mg/5 mL) — Liquid form, measured with a dosing device. Often used for children.
• Oral soluble film (Zuplenz) (4 mg, 8 mg) — A thin film that dissolves on the tongue.
• Injectable solution (2 mg/mL) — Given by IV or intramuscular injection in hospitals and clinics.

Typical Dosing

Dosing depends on why you're taking Ondansetron:

• Chemotherapy: 24 mg as a single dose or 8 mg every 8-12 hours
• Surgery: 16 mg taken 1 hour before anesthesia (oral) or 4 mg IV
• General nausea: 4 to 8 mg every 8 hours as needed

Always follow your doctor's specific instructions. Do not take more than prescribed. Patients with severe liver problems should not exceed 8 mg per day.

Who Should Not Take Ondansetron?

Ondansetron is not right for everyone. You should not take it if you have:

• A known allergy to Ondansetron or other 5-HT3 receptor antagonists (like Granisetron or Palonosetron)
• Congenital long QT syndrome — a heart condition that increases the risk of dangerous arrhythmias
• Are taking Apomorphine — combining these drugs can cause severe low blood pressure and loss of consciousness

Use caution and talk to your doctor if you have:

• Liver disease or impairment
• Heart rhythm problems or a history of heart disease
• Low potassium or magnesium levels
• Are taking medications that affect serotonin levels (see drug interactions)

For a full list of side effects and safety information, see our dedicated guide.

How Much Does Ondansetron Cost?

Ondansetron is available as an affordable generic medication. Here's what you can expect to pay in 2026:

• Generic Ondansetron tablets (with discount card): $4 to $25 for 12-30 tablets
• Generic Ondansetron ODT: $15 to $40 for 12-30 tablets
• Cash price without discounts: $10 to $50 for generic; $300 to $900+ for brand-name Zofran
• With insurance: Typically $0 to $15 copay — generic Ondansetron is usually Tier 1 (preferred generic) on most plans

The best way to save money is to use generic Ondansetron with a prescription discount card from GoodRx, SingleCare, or a similar service. For more tips, see our complete guide to saving money on Ondansetron.

Final Thoughts

Ondansetron is a safe, effective, and affordable anti-nausea medication that has been used for decades. Whether you're taking it for chemotherapy side effects, surgery recovery, morning sickness, or a stomach bug, it's one of the most reliable options available.

If you have a prescription and need help finding Ondansetron in stock, Medfinder can show you which pharmacies near you have it available right now.