NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Ondansetron

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

A selective serotonin 5-HT3 receptor antagonist used for the prevention and treatment of nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. Ondansetron is one of the most widely prescribed antiemetics and is also commonly used off-label for acute gastroenteritis-related nausea.

Evidence tier
Strong
Indexed sources
10 2014–2023
Interactions
0
Category
Prescription
Read the sources → Compare profiles
Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

A selective serotonin 5-HT3 receptor antagonist used for the prevention and treatment of nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. NutriStack rates the supporting evidence as strong. Common adult dosing is 4–8 mg every 8 hours as needed; up to 24 mg for highly emetogenic chemotherapy (as prescribed by your physician), though a prescriber sets the actual dose. This profile indexes 10 sources.

What it's good for
  • Prevention of chemotherapy-induced nausea and vomiting10,6
  • Prevention of radiation-induced nausea and vomiting10,6
  • Prevention of postoperative nausea and vomiting10
  • Off-label: acute gastroenteritis nausea9,10
What to watch for
  • Headache
  • Constipation
  • Dizziness
  • Known hypersensitivity to ondansetron or other 5-HT3 antagonists1,2
  • Concurrent use with apomorphine (risk of severe hypotension)4

The bottom line

Evidence rating strong. Most-documented uses: prevention of chemotherapy-induced nausea and vomiting, prevention of radiation-induced nausea and vomiting, prevention of postoperative nausea and vomiting. 10 sources indexed (2014–2023), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Selectively blocks serotonin (5-hydroxytryptamine, 5-HT3) receptors both peripherally on vagal nerve terminals in the GI tract and centrally in the chemoreceptor trigger zone (CTZ) of the area postrema. By blocking 5-HT3 receptors, ondansetron prevents the initiation of the vomiting reflex triggered by serotonin release from enterochromaffin cells.

Class
Antiemetic (5-HT3 Antagonist)
Dosing

Dosing & protocol.

Common range
4–8 mg every 8 hours as needed; up to 24 mg for highly emetogenic chemotherapy (as prescribed by your physician)
Recommended form
Oral tablet, orally disintegrating tablet (ODT), or IV injection

Can be taken with or without food; ODT dissolves on tongue without water

Safety

Full safety detail.

Side effects

  • Headache
  • Constipation
  • Dizziness
  • Fatigue
  • QT prolongation (dose-dependent)
  • Injection site reactions (IV form)

Contraindications

  • Known hypersensitivity to ondansetron or other 5-HT3 antagonists1,2
  • Concurrent use with apomorphine (risk of severe hypotension)4
  • Congenital long QT syndrome
  • Caution with other QT-prolonging medications
  • Severe hepatic impairment (maximum 8 mg/day)
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Meta-analyses & systematic reviews

7

Reference material

3
FAQ

Common questions.

Quick answers about Ondansetron, drawn from the data on this page.

What is Ondansetron?

A selective serotonin 5-HT3 receptor antagonist used for the prevention and treatment of nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. Ondansetron is one of the most widely prescribed antiemetics and is also commonly used off-label for acute gastroenteritis-related nausea.

What is Ondansetron used for?

Commonly cited benefits of Ondansetron include: Prevention of chemotherapy-induced nausea and vomiting; Prevention of radiation-induced nausea and vomiting; Prevention of postoperative nausea and vomiting; Off-label: acute gastroenteritis nausea. NutriStack rates the overall evidence as strong.

What is a typical dose of Ondansetron?

A typical adult dose of Ondansetron is 4–8 mg every 8 hours as needed; up to 24 mg for highly emetogenic chemotherapy (as prescribed by your physician). The commonly recommended form is Oral tablet, orally disintegrating tablet (ODT), or IV injection. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Ondansetron?

Reported side effects include headache, constipation, dizziness, fatigue, qt prolongation (dose-dependent), injection site reactions (iv form). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Ondansetron?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

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NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.