Ondansetron

ATC code

A04AA01

Therapeutic class

Antiemetic and antinauseant · Serotonin (5-HT3) receptor antagonist

Forms

oral tablet, film-coated tablet, orodispersible tablet, oral solution, injection

Brand names

ondansetron hydrochloride (US) · Zofran (US) · Ondansetron Normon (ES) · Ondansetron Zentiva (FR)

Overall confidence

high

Regulatory sources consulted

openfda-label-cb0b89ea-904e-424e-9213-80fc4d073fe3
aemps-cima-ft-69378
ansm-bdpm-rcp-68663863
PubMed PMID:40673584 ↗
PubMed PMID:38311315 ↗
PubMed PMID:36791365 ↗
PubMed PMID:39140906 ↗
PubMed PMID:41770539 ↗
CredibleMeds.org
OpenFDA · A04AA01
RxNorm rxcui 26225 ↗

Approved indications

Prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy.
Prevention of nausea and vomiting associated with moderately emetogenic cancer chemotherapy.
Prevention of nausea and vomiting associated with radiotherapy.
Prevention of postoperative nausea and/or vomiting (PONV).
Nausea and vomiting of pregnancy (NVP) and hyperemesis gravidarum (HG) refractory to first-line treatment. · off-label
Treatment of vomiting associated with acute gastroenteritis in children. · off-label
Abortive therapy for acute episodes of cyclic vomiting syndrome (CVS). · off-label

Contraindications

Absolute

Known hypersensitivity to ondansetron or any of the components of the formulation.
Concomitant use of apomorphine, due to the risk of profound hypotension and loss of consciousness.

Clinical warnings

Major warning · QT Interval Prolongation: Ondansetron prolongs the QT interval in a dose-dependent manner, which can lead to Torsades de Pointes. Avoid in patients with congenital long QT syndrome. — FDA
Major warning · Serotonin Syndrome: Has been described following concomitant use of 5-HT3 antagonists and other serotonergic drugs (e.g., SSRIs, SNRIs). — FDA
Myocardial Ischemia: Cases have been reported, primarily during intravenous administration. — ANSM
Masking of Progressive Ileus and/or Gastric Distension: Postoperative use may mask an ileus or gastric distension. — FDA

Drug interactions

HighApomorphineN04BC07
Mechanism: Pharmacodynamic interaction resulting in profound hypotension and loss of consciousness.
Recommendation: Concomitant use is contraindicated.
FDA labelANSM RCP
HighSerotonergic drugs (SSRIs, SNRIs, MAOIs, Tramadol)N06A
Mechanism: Additive serotonergic effects which may precipitate serotonin syndrome.
Recommendation: Monitor for symptoms of serotonin syndrome. If symptoms occur, discontinue treatment and initiate supportive care.
FDA labelANSM RCP
HighQT-prolonging drugs (e.g. amiodarone, sotalol, doxorubicin)C01BD01
Mechanism: Additive effect on QT interval prolongation, increasing the risk of ventricular arrhythmias such as Torsades de Pointes.
Recommendation: Use with caution. Consider ECG monitoring. Correct hypokalemia and hypomagnesemia before administration.
ANSM RCP
ModerateTramadolN02AX02
Mechanism: Ondansetron may reduce the analgesic effect of tramadol.
Recommendation: Monitor to ensure adequate pain control.
FDA label

Adverse events

Common (≥1%)

headache · constipation · sensation of warmth or flushing · malaise/fatigue · diarrhea

Rare but serious

QT prolongation (Torsades de Pointes) · serotonin syndrome · myocardial ischemia · anaphylactic reactions · transient blindness · Stevens-Johnson syndrome/toxic epidermal necrolysis

Pregnancy and lactation

Should not be used during the first trimester of pregnancy due to a small increased risk of orofacial clefts. Contraception should be considered in women of childbearing potential. Ondansetron is excreted in breast milk; use is not recommended during breastfeeding.

Recent literature (PubMed)

Multidose Ondansetron after Emergency Visits in Children with Gastroenteritis.
Freedman SB, et al. · N Engl J Med · 2025 · Relevance 5/5
Un ensayo aleatorizado doble ciego en 1030 niños con gastroenteritis demostró que el ondansetrón administrado en casa después de una visita a urgencias redujo significativamente el riesgo de gastroenteritis de moderada a severa en comparación con el placebo (OR ajustado 0.50). También redujo el número total de episodios de vómitos.
The Management of Nausea and Vomiting in Pregnancy and Hyperemesis Gravidarum (Green-top Guideline No. 69).
Nelson-Piercy C, et al. · BJOG · 2024 · Relevance 5/5
Esta guía del RCOG posiciona al ondansetrón como un antiemético seguro y eficaz de segunda línea para las náuseas y vómitos del embarazo (NVE) y la hiperémesis gravídica (HG). Recomienda tranquilizar a las mujeres sobre el muy pequeño aumento del riesgo absoluto de hendiduras orofaciales, que debe sopesarse con los riesgos de una HG mal controlada.
Diagnosis and Management of Cyclic Vomiting Syndrome: A Critical Review.
Frazier R, et al. · Am J Gastroenterol · 2023 · Relevance 4/5
Revisión crítica sobre el síndrome de vómitos cíclicos (SVC) que recomienda el ondansetrón como parte de la terapia abortiva para los episodios agudos, junto con triptanes y sedación. Destaca la importancia de un enfoque biopsicosocial para el manejo de esta compleja patología de la interacción intestino-cerebro.
AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review.
Kothari S, et al. · Gastroenterology · 2024 · Relevance 4/5
Actualización de la práctica clínica de la AGA que revisa el manejo de enfermedades gastrointestinales en el embarazo. Apoya el tratamiento temprano de las náuseas y vómitos del embarazo para reducir la progresión a hiperémesis gravídica y recomienda un enfoque escalonado para los antieméticos, donde el ondansetrón juega un papel importante.
Chronic, Noninfectious Diarrhea: A Review.
Singh P, et al. · JAMA · 2026 · Relevance 2/5
Esta revisión sobre la diarrea crónica menciona brevemente el uso de antagonistas 5-HT3 como el ondansetrón para el tratamiento de la diarrea por ácidos biliares, una causa de diarrea crónica. La relevancia para el uso principal de ondansetrón como antiemético es baja.