ondansetron vs palonosetron
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of ondansetron and palonosetron. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
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Ondansetron is a medicine that helps prevent nausea and vomiting. It is often used during cancer treatment or after surgery.
Palonosetron is a medicine that helps prevent nausea and vomiting. It is often used before, during, and after chemotherapy or surgery.
This medicine is used to prevent nausea and vomiting. It can help if you are getting chemotherapy for cancer. It also helps with nausea and vomiting after surgery or radiation.
Palonosetron is used to prevent nausea and vomiting caused by cancer chemotherapy. It can prevent these side effects from both the first treatment and any repeat treatments. Palonosetron is also used to prevent nausea and vomiting after surgery.
Ondansetron blocks a natural substance in your body called serotonin. Serotonin can cause nausea and vomiting. By blocking serotonin, ondansetron reduces these side effects.
Palonosetron blocks a natural substance in your body called serotonin. Serotonin can trigger nausea and vomiting. By blocking serotonin, palonosetron helps prevent these symptoms.
- • Headache
- • Feeling tired
- • Constipation
- • Diarrhea
- • Headache
- • Constipation
- Nausea 11,554
- Fatigue 8,199
- Diarrhoea 7,791
- Vomiting 7,326
- Death 4,872
- Nausea 399
- Fatigue 249
- Febrile Neutropenia 249
- Diarrhoea 246
- Vomiting 246
Ondansetron can cause heart problems like a prolonged QT interval. If you have congenital long QT syndrome, you should not take this medicine. Ondansetron can also cause Serotonin Syndrome, especially if you are taking other medicines for depression or pain. Seek immediate medical attention if you experience chest pain.
Palonosetron can cause serious allergic reactions, including anaphylaxis. Tell your doctor right away if you have any signs of an allergic reaction, such as hives, difficulty breathing, or swelling of your face, lips, tongue, or throat. Palonosetron can also cause serotonin syndrome, especially if you are taking other medicines that affect serotonin. Symptoms may include agitation, hallucinations, fast heart rate, fever, and muscle stiffness.
Talk to your doctor if you are pregnant or breastfeeding. It is not known if ondansetron will harm your unborn baby. Studies on the risk of birth defects are inconsistent.
It is not known if palonosetron can harm an unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if palonosetron passes into breast milk. Talk to your doctor about the best way to feed your baby if you are taking palonosetron.
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How to Read This ondansetron vs palonosetron Comparison
ondansetron is classified in the 5-HT3 Receptor Antagonist (Antiemetic) drug class, while palonosetron sits within the 5-HT3 Receptor Antagonist (Antiemetic) class. Because both drugs share the same classification, they are often considered interchangeable in theory, but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, ondansetron has 39,742 submissions while palonosetron has 1,389. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for ondansetron or palonosetron.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.