Palonosetron vs. Ondansetron for Nausea: Important Differences and Potential Risks.

Key takeaways

Palonosetron (Aloxi) and ondansetron (Zofran) are both antiemetic medications used to prevent nausea and vomiting caused by chemotherapy and surgery. They belong to the same drug class, serotonin antagonists, and work by blocking serotonin in the brain. However, they differ in several ways. Palonosetron is only available as an intravenous (IV) injection, while ondansetron can be taken orally as tablets, orally disintegrating tablets (ODT), or liquid, and also as an injection. Palonosetron is typically given as a single dose before chemotherapy or surgery, whereas ondansetron is taken multiple times a day. Both medications are available as a lower-cost generic. Common side effects of palonosetron include headache and constipation, while ondansetron can cause headache, fatigue, and constipation or diarrhea. Both medications can interact with other drugs that affect serotonin levels, but ondansetron also has a risk of causing heart rhythm problems.

Palonosetron

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Ondansetron

(Zofran)

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Summary for Palonosetron

Prescription only

Palonosetron is a medication that's used to prevent nausea and vomiting from cancer medications (chemotherapy) and surgery. The dose is usually a one-time injection through the veins that's given by a healthcare provider in a clinic or hospital. The most common side effects are headache and constipation. Palonosetron is still available as a generic medication, but its brand name Aloxi is now discontinued.

Indications for Palonosetron

Prevention of nausea and vomiting from chemotherapy in adults and children 1 month of age and older
Prevention of nausea and vomiting (for up to 24 hours) after surgery in adults

Pros and Cons for Palonosetron

Pros

Might work better and have less side effects than other antiemetics in the same drug class
Long-lasting medication that's given as a single dose before chemotherapy or surgery
Can use for young children age 1 month and older who are receiving chemotherapy

Cons

Can only be given by IV injection (into the vein)
Must be given by a healthcare professional
Side effects might last a long time

Common Side Effects for Palonosetron

Headache (9%)
Constipation (5%)

Warnings for Palonosetron

Allergic reactions
Serotonin syndrome

Summary for Ondansetron

Prescription only

Ondansetron (Zofran) is an antiemetic (or anti-nausea) medication. It's used to prevent nausea and vomiting after surgery or cancer treatments. It works by stopping a chemical called serotonin from binding to receptors in the brain that cause the feeling of nausea and vomiting. Ondansetron (Zofran) is taken by mouth, typically every 8 to 12 hours. It comes in different formulations, including orally disintegrating tablet (ODT) and oral solution. It can also be given as injection by a healthcare professional (HCP) in a hospital setting. Side effects of this medication include headache, tiredness, and constipation or diarrhea.

Indications for Ondansetron

Prevention of nausea and vomiting due to cancer medications (chemotherapy) or radiation therapy
Prevention of nausea and vomiting after surgery

Pros and Cons for Ondansetron

Pros

Can use for both adults and children
Available as a lower-cost generic
Available as a liquid, dissolvable tablet, and injection for people who have problems swallowing pills or are too nauseous to keep medication down
Possible option during pregnancy and breastfeeding

Cons

Needs to be taken multiple times daily
Might cause headache
Can interact with certain medications, like antidepressants and migraine medications
Not the best option for people who are at risk for stomach or gut blockages (bowel problems)

Common Side Effects for Ondansetron

Headache (up to 24%)
Fatigue (up to 13%)
Constipation (up to 9%)
Diarrhea (up to 6%)

Warnings for Ondansetron

Severe allergic reactions
Life-threatening abnormal heart rhythm (QT prolongation)
Serotonin syndrome
Risk of heart attack
Masking of gut blockage and stomach bloating
Caution use in people with phenylketonuria (PKU) - orally disintegrating tablets only