Ondansetron
Ondansetron is an antiemetic medication used to prevent and treat nausea and vomiting caused by chemotherapy, radiation therapy, and surgery.
Ondansetron is a 5-HT3 receptor antagonist used to prevent and treat nausea and vomiting associated with chemotherapy, radiation, and surgery.
Key facts at a glance
- ATC
- A04AA01
- Generic
- Ondansetron
- Class
- antiemetic
- Brands
- Zofran
- Availability
- rx
- Pregnancy
- B
- Lactation
- caution
- Half-life (h)
- 4
- Onset (min)
- 30
- Duration (h)
- 8
- Routes
- oral, iv, im
- Forms
- tablet, injection, oral-disintegrating
- Regions
- CN, US, EU, JP
- Monitoring
- cardiac-qt
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 8mg every 8 hours
- Maximum
- consult physician
- Frequency
- every 8 hours as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 4mg every 8 hours
- Maximum
- consult physician
- Frequency
- every 8 hours as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 8mg every 8 hours
- Maximum
- consult physician
- Frequency
- every 8 hours as needed
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
7 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks; consider alternative antiemetics
regular fetal monitoring
Use with caution and monitor for adverse effects.
pregnancy
second and third trimesteruse lowest effective dose
use only if clearly needed for severe nausea/vomiting
standard prenatal care
Use with caution and monitor for adverse effects.
lactation
breastfeedingnone
compatible with breastfeeding; minimal infant exposure
none required
geriatric
elderly 65 years and olderno specific adjustment; start low
use with caution due to QT prolongation risk; monitor cardiac function
periodic ECG monitoring recommended
Use with caution and monitor for adverse effects.
pediatric_age
children 6 months to 18 yearsweight-based dosing required
use appropriate pediatric formulation; do not exceed recommended doses
monitor for signs of QT prolongation
renal_impairment
severe creatinine clearance less than 30 ml minreduce dose to 8mg daily
reduce dose in severe renal impairment; no adjustment for mild to moderate
monitor renal function periodically
Use with caution and monitor for adverse effects.
hepatic_impairment
severe hepatic impairmentreduce maximum daily dose to 8mg
reduce dose in severe hepatic impairment; clearance decreased
monitor liver function tests
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA approval year
FDA approval for Ondansetron (Zofran)
Drug class
Pharmacological classification
Primary indication
Main therapeutic use
Mechanism of action
Pharmacodynamic properties
Prevents chemotherapy-induced nausea and vomiting (CINV), radiation-induced nausea, and post-operative nausea and vomiting (PONV). Also sometimes used for gastroenteritis-related vomiting, particularly in emergency settings.
Blocks 5-HT3 serotonin receptors in the chemoreceptor trigger zone (CTZ) of the brain, preventing serotonin signals that would normally trigger nausea and vomiting. Available in oral, IV, and intramuscular formulations for flexible dosing.
May cause headache, constipation, or dizziness. Use with caution in patients with heart conditions as it can prolong QT interval. Generally not recommended in first trimester of pregnancy. Effectiveness may vary between patients; other antiemetics may be needed for breakthrough nausea.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy