Non-peptide
Ondansetron
Ondansetron, sold as Zofran, is FDA-approved to prevent nausea and vomiting from cancer treatment and surgery. For that use the evidence grade is strong-human. Its use for nausea in pregnancy is not approved. It can upset the heart's rhythm.
This page has not been individually reviewed by a clinician.
Fact sheet · 6 facts
every row cites its source and its date| Fact | Value | Tier | Checked | Source |
|---|---|---|---|---|
| Also called | Zofran, Zofran ODT, ondansetron hydrochloride | primary | accessdata.fda.gov | |
| Class | non-peptide | primary | accessdata.fda.gov | |
| Regulatory status | fda-approved | primary | accessdata.fda.gov | |
| Status source read | 2026-10-26 | primary | accessdata.fda.gov | |
| Evidence grade | strong-human | our assessment | peptideindex.ai | |
| Label dosing | From the Zofran labels. By mouth, adults take a single 24 mg dose 30 minutes before highly nausea-causing chemotherapy. Before other chemotherapy, adults take 8 mg 30 minutes before it and 8 mg 8 hours later. Then they take 8 mg every 12 hours for 1 to 2 days after it ends. Before surgery, adults take 16 mg an hour before anesthesia. By vein before chemotherapy, the dose is 0.15 mg per kilogram, up to 16 mg, given three times. People with severe liver disease take no more than 8 mg a day. The prescriber sets the dose. | primary | accessdata.fda.gov |
Short answer
Ondansetron, sold as Zofran, is FDA-approved to prevent nausea and vomiting from cancer treatment and surgery. For that use the evidence grade is strong-human. Its use for nausea in pregnancy is not approved. It can upset the heart's rhythm.
Our assessment, drawn from the sources below.
What it is
Ondansetron is a drug that prevents nausea and vomiting [1]. It blocks one kind of serotonin receptor, called 5-HT3 [1]. It is not a peptide.
It comes as a tablet, a tablet that melts on the tongue, a liquid to swallow and a shot [1] [2]. Zofran is the brand name [1]. FDA first approved it in 1991 [1].
Where it stands legally
Ondansetron is FDA-approved: Drugs@FDA lists Zofran tablets, Zofran shots and Zofran tablets that melt on the tongue as approved drugs [3] [4] [5]. The approval covers nausea and vomiting from cancer drugs, radiation and surgery [1] [2]. It does not cover nausea in pregnancy, which is an off-label use [17] [18]. Checked 26 October 2026.
Drugs@FDA lists the Zofran brand products as no longer sold. A Federal Register notice says they were not pulled for safety reasons [3] [4] [5]. One high dose was different. In 2015, FDA found that a 32 mg single dose into a vein was pulled from sale for reasons of safety [6].
In 2023, a federal appeals court upheld the dismissal of hundreds of birth defect lawsuits [17] [18]. It found FDA would have rejected the pregnancy warning the families wanted [18].
Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug [7]. Ondansetron is not on FDA's 503A category list [8].
What the evidence shows
Evidence grade: strong-human · our assessment
The evidence grade is strong-human for stopping vomiting after surgery and from a stomach bug in children [11] [13]. A 2020 review pooled 585 studies of drugs used during surgery [13]. It found high-certainty evidence that ondansetron cuts vomiting in the first day [13].
In a 2006 trial, 215 children with a stomach bug got one dose or a dummy pill [11]. Of those on the drug, 14% vomited, against 35% on the dummy pill [11]. A 2011 review of seven trials found it cut the need for a drip and a hospital stay [12].
For nausea in pregnancy, a 2016 review linked it to fewer symptoms [14]. The review rated the evidence as low quality [14]. In a 2014 trial of 36 women, it eased nausea more than doxylamine and pyridoxine [15].
On safety in pregnancy, studies disagree. A 2013 study of pregnancies in Denmark found no rise in birth defects or miscarriage [10]. A 2018 US study found a small rise in oral clefts [9]. A 2023 study in rats found no birth defects in the pups [16].
Known risks
- It can change the heart's electrical rhythm, called QT prolongation. Rare cases of a deadly rhythm, torsade de pointes, have been reported [1] [2].
- FDA found that a 32 mg single dose into a vein was pulled from sale for reasons of safety. That dose raised the heart rhythm risk [6].
- Serotonin syndrome has been reported, mostly in people who also took some antidepressants or opioids. Some cases were fatal [1].
- Taken with apomorphine, it can cause a big drop in blood pressure and passing out. The label says not to combine them [1].
- Some people have had bad allergic reactions. A few had trouble breathing [1].
- Reduced blood flow to the heart has been reported, mostly when it was given into a vein [1].
- After belly surgery or cancer drugs, it can hide a blocked bowel [1].
- In the label's studies, the most common problems were headache and feeling tired. Others were constipation and diarrhea [1].
- A 2018 US study of 1.8 million pregnancies found a small rise in oral clefts, a split lip or palate, with use in the first three months [9].
What nobody knows yet
- Nobody knows for sure if it harms a baby in early pregnancy. The label says studies have found mixed results [1] [9] [10].
- A 2016 review of nausea in pregnancy found the evidence was of low quality [14].
- The 2014 trial in pregnant women was small. Only 36 women took part [15].
- After surgery, a 2020 review found only low or very low certainty about serious harms. It called for more studies of harms [13].
Legitimate ways to get it
The legal way to get ondansetron is a prescription [1] [2]. Its labels cover nausea and vomiting from cancer drugs, radiation and surgery [1] [2]. The Zofran brand products are listed as no longer sold [3] [4] [5].
Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug [7].
US trials that use ondansetron are open, such as one comparing it with fosaprepitant for nausea [19]. The trials block on this page lists open trials with their dates.
Approved product
Approved by FDA as a prescription drug. Drugs@FDA lists the Zofran brand products as no longer sold.
Brand names: Zofran, Zofran ODT
Manufacturer: Sandoz
Indication: Prevention of nausea and vomiting from cancer chemotherapy, radiotherapy and surgery.
Lawful compounding
Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug.
Recruiting trials
A listing is not a recommendation. Trials have strict eligibility rules. Talk to your doctor and read the official record.
Snapshot of .clinicaltrials.gov
NCT05784350
Preoperative Point of Care Ultrasound Guided Fluid Optimization and Intravenous Ondansetron to Prevent General Anesthesia-Induced Hypotension
Phase: Not applicable · Sponsor: Meir Medical Center · Status: Not yet recruiting
Countries: Israel
US states: none listed
NCT07891312
Amisulpride Injection for the Prevention of Postoperative Nausea and Vomiting in Patients Undergoing Laparoscopic Surgery
Phase: Not applicable · Sponsor: Qianfoshan Hospital · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07795060
Ondansetron to Prevent Oral Rehydration Failure in Children With Cholera
Phase: Phase 2 · Sponsor: Public Interest Science Center · Status: Not yet recruiting
Countries: Republic of the Congo
US states: none listed
NCT07588217
Ondansetron for the Prevention of Patient Self-Inflicted Lung Injury in Patients With ARDS - Pilot RCT
Phase: Phase 2/Phase 3 · Sponsor: Centre Integre Universitaire de Sante et Services Sociaux du Nord de l'ile de Montreal · Status: Not yet recruiting
Countries: Canada
US states: none listed
NCT07848984
Chinese Herbal Acupoint Application Combined With Triple Antiemetic Therapy for Prevention of Chemotherapy-Induced Nausea and Vomiting in Breast Cancer
Phase: Phase 2 · Sponsor: Second Affiliated Hospital, Zhejiang University, School of Medicine · Status: Not yet recruiting
Countries: China
US states: none listed
NCT07793760
Dexamethasone Versus Ondansetron for Preventing Post-Spinal Hypotension in Preeclampsia
Phase: Phase 4 · Sponsor: Assiut University · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07858149
Effects of Ondansetron Timing During Spinal Anesthesia for Urologic Surgery
Phase: Phase 4 · Sponsor: Istanbul University · Status: Not yet recruiting
Countries: Turkey (Türkiye)
US states: none listed
NCT07868861
A Study to Compare the Bioavailability of Ondansetron Following Nasal (NS003) and IV Administration in Healthy Adults
Phase: Phase 1 · Sponsor: Nasus Pharma · Status: Recruiting
Countries: Israel
US states: none listed
NCT07813975
Evaluating the Impact of Vitamin D Supplementation on Healing Bed Sores in ICU.
Phase: Not applicable · Sponsor: Maha Salah · Status: Recruiting
Countries: Egypt
US states: none listed
NCT07681076
Study to Assess Safety and Tolerability of KarXT With Administration of Antiemetics in Healthy Volunteers
Phase: Phase 4 · Sponsor: Karuna Therapeutics, Inc., a Bristol Myers Squibb company · Status: Recruiting
Countries: United States
US states: California, Florida, Georgia
NCT07761312
Afentanil and Remifentanil for Anesthesia Quality and Recovery
Phase: Phase 4 · Sponsor: Qianfoshan Hospital · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07638527
Time to First Rescue Antiemetic With Ondansetron Plus Metoclopramide Versus Dexamethasone Plus Metoclopramide for PONV Prophylaxis in Laparoscopic Cholecystectomy
Phase: Phase 4 · Sponsor: Faisalabad Medical University · Status: Recruiting
Countries: Pakistan
US states: none listed
NCT07777276
Sleep Quality - Comparing the Effect of Ondansetron or Dexamethasone Given as Routine Prophylaxis Intraoperatively to Prevent Post Operative Nausea and Vomiting (SCORPION)
Phase: Phase 4 · Sponsor: Telethon Kids Institute · Status: Not yet recruiting
Countries: Australia, Brazil
US states: none listed
NCT07662200
A Simplified Regimen to Prevent Nausea and Vomiting Using Netupitant/Palonosetron in Germ Cell Cancer Patients Receiving Chemotherapy
Phase: Early phase 1 · Sponsor: Ottawa Hospital Research Institute · Status: Not yet recruiting
Countries: Canada
US states: none listed
NCT07740577
Routine Antiemetic Prophylaxis for Nonfasted Parturients Undergoing Cesarean Sections Under Spinal Anesthesia
Phase: Phase 4 · Sponsor: Sanliurfa Education and Research Hospital · Status: Recruiting
Countries: Turkey (Türkiye)
US states: none listed
NCT07697625
A Clinical Trial of MK-4082 in Healthy Participants (MK-4082-005)
Phase: Phase 1 · Sponsor: Merck Sharp & Dohme LLC · Status: Recruiting
Countries: United States
US states: California
NCT07768124
Acupoint Application for Chemotherapy-Induced Nausea and Vomiting in Lung Cancer
Phase: Not applicable · Sponsor: Xiu Huang · Status: Recruiting
Countries: China
US states: none listed
NCT07639723
Aprepitant to Improve Same Day Discharge for TKA
Phase: Phase 4 · Sponsor: Endeavor Health · Status: Not yet recruiting
Countries: United States
US states: Illinois
NCT07643285
Feasibility and Safety of a Pediatric ERAS Protocol for Laparoscopic Appendectomy
Phase: Not applicable · Sponsor: Ahmet Burak Doğan, MD · Status: Recruiting
Countries: Turkey (Türkiye)
US states: none listed
NCT07632144
Ondansetron Versus Lidocaine for Preventing Pain on Propofol Injection.
Phase: Not applicable · Sponsor: Mongi Slim Hospital · Status: Not yet recruiting
Countries: Tunisia
US states: none listed
NCT07706348
Intraperitoneal Irrigation of Ondansteron in Combination With Lidocaine in Acute Postoperative Pain
Phase: Phase 1/Phase 2 · Sponsor: Assiut University · Status: Recruiting
Countries: Egypt
US states: none listed
NCT07558226
Multimodal Anesthesia in Robotic Laparoscopic Nephrectomy
Phase: Not applicable · Sponsor: Fundacio Puigvert · Status: Recruiting
Countries: Spain
US states: none listed
NCT07603596
Opioid-free Anesthesia and Postoperative Delirium
Phase: Phase 1 · Sponsor: Qianfoshan Hospital · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07381634
The Safety and Efficacy of Ondansetron in Reducing Immune Checkpoint Inhibitor-Related Toxicities
Phase: Phase 2 · Sponsor: First Affiliated Hospital of Wenzhou Medical University · Status: Recruiting
Countries: China
US states: none listed
NCT07511491
Ondansetron Lozenge Versus Intravenous for Prevention of Shivering in Cesarean Section
Phase: Not applicable · Sponsor: Tanta University · Status: Recruiting
Countries: Egypt
US states: none listed
NCT07455955
Personalized Antiemetic Regimen According to Patients' Pharmacogenetic Profile
Phase: Phase 2 · Sponsor: Chinese University of Hong Kong · Status: Recruiting
Countries: Hong Kong
US states: none listed
NCT07489742
Ondansetron Lozenge Versus Intravenous for Prevention of Shivering in Tonsillectomy
Phase: Not applicable · Sponsor: Tanta University · Status: Recruiting
Countries: Egypt
US states: none listed
NCT07458295
The Efficacy and Safety of Liposomal Bupivacaine for Transversus Abdominis Plane Block in Relieving Postoperative Pain After Laparoscopic Surgery in Gynecologic Oncology
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07458282
The Efficacy and Safety of Liposomal Bupivacaine for Transversus Abdominis Plane Block in Relieving Postoperative Pain After Laparoscopic Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07458256
The Efficacy and Safety of Liposomal Bupivacaine in Relieving Postoperative Pain After Laparoscopic Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07442539
The Efficacy and Safety of Liposomal Bupivacaine in Relieving Postoperative Pain After Hemorrhoid Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07432711
The Efficacy and Safety of Liposomal Bupivacaine in Relieving Postoperative Pain After Video-assisted Thoracoscopic Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07441902
The Efficacy and Safety of Liposomal Bupivacaine for Rhomboid Intercostal Nerve Block in Relieving Postoperative Pain After Video-assisted Thoracoscopic Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07330999
Three Variants of the PENG Block With and Without Perineural Adjuvants in Older Adults
Phase: Not applicable · Sponsor: Poznan University of Medical Sciences · Status: Recruiting
Countries: Poland
US states: none listed
NCT07699276
Steroid Sparing Regimen With Olanzapine and Palonosetron for Emetic Prevention for High Dose Cisplatin
Phase: Phase 2 · Sponsor: Mahidol University · Status: Recruiting
Countries: Thailand
US states: none listed
NCT07377903
Post Operative Shivering Following Anesthesia
Phase: Not applicable · Sponsor: Sohag University · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07607990
Effects of Rectal Indomethacin Suppository on Postoperative CRBD in Patients Undergoing LRP
Phase: Not applicable · Sponsor: Zhejiang University · Status: Recruiting
Countries: China
US states: none listed
NCT07361822
Comparison of Cumulative Opioid Consumption Between Variable-Rate Feedback Infusion and Fixed-Rate Basal Infusion Modes of Intravenous PCA Following Mixed Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07375121
Comparison of the Efficacy and Safety of Fixed-rate Basal Infusion Mode and Time-programmed Decremental Background Infusion Mode of Intravenous PCA Following Mixed Surgery
Phase: Not applicable · Sponsor: Beijing Tiantan Hospital · Status: Recruiting
Countries: China
US states: none listed
NCT07246070
Nano-crystalline Megestrol Acetate for Chemotherapy-induced Nausea and Vomiting
Phase: Phase 2 · Sponsor: AIPING ZHOU · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT06869967
Evaluation of Postoperative Pain Control in Ear Surgery
Phase: Not applicable · Sponsor: Kocaeli University · Status: Recruiting
Countries: Turkey (Türkiye)
US states: none listed
NCT06953570
Impact of Frailty on Nalbuphine Dose for Postoperative Analgesia in Elderly Patients Undergoing Laparoscopic GI Surgery
Phase: Not stated · Sponsor: Yongtao Sun · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT07164677
Serratus Posterior Superior Plane Block for Postoperative Pain in Cardiac Surgery
Phase: Not applicable · Sponsor: Ondokuz Mayıs University · Status: Recruiting
Countries: Turkey (Türkiye)
US states: none listed
NCT06952920
Electroacupuncture for Chemotherapy-Induced GI Symptom Clusters in Breast Cancer
Phase: Phase 3 · Sponsor: Jiuda Zhao · Status: Recruiting
Countries: China
US states: none listed
NCT07124195
Nanocrystalline Megestrol for Managing Chemotherapy-Induced Nausea and Vomiting
Phase: Phase 3 · Sponsor: The First Affiliated Hospital of Xinxiang Medical College · Status: Not yet recruiting
Countries: China
US states: none listed
NCT07088601
Efficacy of Oral Ondansetron Strips on Prevention of Post-Spinal Shivering
Phase: Phase 4 · Sponsor: Cairo University · Status: Not yet recruiting
Countries: none listed
US states: none listed
NCT06530563
the Efficacy and Safety of Oliceridine Fumarate Injection for Acute Pain After Abdominal Surgery
Phase: Phase 4 · Sponsor: Xiangya Hospital of Central South University · Status: Not yet recruiting
Countries: China
US states: none listed
NCT07084753
Non-opioid Anesthesia Based on Thoracic Paravertebral Block During Laparoscopic Sleeve Gastrectomy
Phase: Not applicable · Sponsor: IVO JURISIC · Status: Not yet recruiting
Countries: Croatia
US states: none listed
NCT06938581
ERAS Protocols in Breast Conserving Surgery
Phase: Not applicable · Sponsor: University of Nebraska · Status: Recruiting
Countries: United States
US states: Nebraska
NCT06904235
Study With IV NEPA (Fosnetupitant/Palonosetron) for the Prevention of Chemotherapy-induced Nausea and Vomiting in Paediatric Cancer Patients Undergoing Highly Emetogenic Chemotherapy (HEC)
Phase: Phase 2 · Sponsor: Helsinn Healthcare SA · Status: Recruiting
Countries: Greece, Poland, Romania, Turkey (Türkiye)
US states: none listed
Sources
- [1]Zofran tablets, orally disintegrating tablets and oral solution label, revised February 2025Label · primary
- [2]Zofran injection label, revised February 2025Label · primary
- [3]Drugs@FDA: Zofran (ondansetron hydrochloride) tablets, application 020103Regulatory · primary
- [4]Drugs@FDA: Zofran (ondansetron hydrochloride) injection, application 020007Regulatory · primary
- [5]Drugs@FDA: Zofran ODT (ondansetron) orally disintegrating tablets, application 020781Regulatory · primary
- [6]Federal Register: 32 mg single-dose ondansetron injection withdrawn from sale for reasons of safety, 10 June 2015Regulatory · primary
- [7]FDA: bulk drug substances used in compounding under section 503ARegulatory · primary
- [8]FDA: 503A bulk drug substances category list, updated May 2026Regulatory · primary
- [9]Cohort study: first-trimester ondansetron, heart defects and oral clefts in US Medicaid pregnancies, 2018Human trial · peer-reviewed
- [10]Cohort study: ondansetron in pregnancy and fetal outcomes in Denmark, 2013Human trial · peer-reviewed
- [11]Randomized trial: oral ondansetron for gastroenteritis in a pediatric emergency department, 2006Rct · peer-reviewed
- [12]Cochrane review: antiemetics for vomiting from gastroenteritis in children, 2011Systematic review · peer-reviewed
- [13]Cochrane network meta-analysis: drugs to prevent nausea and vomiting after surgery, 2020Systematic review · peer-reviewed
- [14]Systematic review: treatments for nausea and vomiting in pregnancy, 2016Systematic review · peer-reviewed
- [15]Randomized trial: ondansetron against doxylamine and pyridoxine for nausea in pregnancy, 2014Rct · peer-reviewed
- [16]Rat study: embryo-fetal safety of ondansetron, 2023Animal · peer-reviewed
- [17]Drug and Device Law: appeals court upholds preemption in the Zofran cases, January 2023Legal analysis · legal-analysis
- [18]Bloomberg Law: Zofran birth injury lawsuits preempted by federal law, January 2023Reference · established-news
- [19]ClinicalTrials.gov NCT06382012: fosaprepitant against ondansetron for nausea and vomitingReference · primary
Last verified · 6 facts · 7 sources
- clinicaltrials.gov
- peptideindex.ai
- peptideindex.ai
- pubmed.ncbi.nlm.nih.gov
- pubmed.ncbi.nlm.nih.gov
- accessdata.fda.gov
- accessdata.fda.gov
Primary source: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=020103
Machine readers: JSON · Markdown · Status history: Change log
Information, not medical advice.
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