Prescription medication · 5-HT3 Receptor Antagonist (Antiemetic)
ondansetron
Also sold as Zofran. This medicine is used to prevent nausea and vomiting.
Data updated 2026-05-15
- 103,354
- FDA reportsOften reported
- 6
- InteractionsFew interactions
- 2
- Recall records
What the data shows
ondansetron (Zofran) is a prescription 5-HT3 Receptor Antagonist (Antiemetic), more reported than most tracked drugs (103,354 FDA reports), with 6 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
ondansetron (Zofran) is a prescription 5-HT3 Receptor Antagonist (Antiemetic). This medicine is used to prevent nausea and vomiting.
Ondansetron is a medicine that helps prevent nausea and vomiting. It is often used during cancer treatment or after surgery.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.31/unit
Generic Available
Yes (34 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
NADAC price trail: ONDANSETRON 4 MG/5 ML SOLUTION
Same CMS presentation as the headline generic unit price above (2 effective dates). Adjacent % compares consecutive NADAC releases for this description only, not a patient out-of-pocket quote. Latest step: +7.5% vs prior release.
| Effective | NADAC / unit | vs prior | NDCs |
|---|---|---|---|
| February 21, 2024 | $0.2901/ML | - | 1 |
| December 18, 2024 | $0.3120/ML | +7.5% | 5 |
What it does
This medicine is used to prevent nausea and vomiting.
Common side effects
Headache, Feeling tired, Constipation
Key warnings
Ondansetron can cause heart problems like a prolonged QT interval.
The sections below are summarized in plain English from ondansetron's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Ondansetron blocks a natural substance in your body called serotonin. Serotonin can cause nausea and vomiting. By blocking serotonin, ondansetron reduces these side effects.
Side Effects (from patient reports)
Based on 103,354 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for ondansetron, by number of reports
- Nausea
Nausea
11,554 reports
- Fatigue
Fatigue
8,199 reports
- Diarrhoea
Diarrhoea
7,791 reports
- Vomiting
Vomiting
7,326 reports
- Death
Death
4,872 reports
- Pyrexia
Pyrexia
4,788 reports
- Dyspnoea
Dyspnoea
4,707 reports
- Febrile Neutropenia 4,495
Febrile Neutropenia
4,495 reports
- Pain 4,367
Pain
4,367 reports
- Headache 4,223
Headache
4,223 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for ondansetron each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where ondansetron sits
ondansetron has more FDA adverse-event reports than 86% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is ondansetron; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 103,354 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2003–2025.
Total Reports
103,354
Reports Mentioning Death
13,423
13.0% of reports — not proof of cause
Hospitalization Reports
47,077
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 11,554 |
| 2 | FATIGUE | 8,199 |
| 3 | DIARRHOEA | 7,791 |
| 4 | VOMITING | 7,326 |
| 6 | DEATH | 4,872 |
| 7 | PYREXIA | 4,788 |
| 8 | DYSPNOEA | 4,707 |
| 9 | FEBRILE NEUTROPENIA | 4,495 |
| 10 | PAIN | 4,367 |
| 11 | HEADACHE | 4,223 |
| 12 | CONSTIPATION | 3,884 |
| 13 | ASTHENIA | 3,662 |
| 15 | PNEUMONIA | 3,446 |
| 16 | DECREASED APPETITE | 3,372 |
| 17 | ACUTE KIDNEY INJURY | 3,369 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Ondansetron can cause heart problems like a prolonged QT interval. If you have congenital long QT syndrome, you should not take this medicine. Ondansetron can also cause Serotonin Syndrome, especially if you are taking other medicines for depression or pain. Seek immediate medical attention if you experience chest pain.
Known Drug Interactions
7.3 Tramadol Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small trials indicate that when used together, ondansetron may increase patient-controlled administration of tramadol. Monitor patients to ensure adequate pain control when ondansetron is administered with tramadol.
Mechanism: Using these drugs together might make the pain reliever less effective, leading patients to need more of it to feel relief.
In a crossover trial in 76 pediatric patients, intravenous ondansetron did not increase systemic concentrations of high-dose methotrexate.
Mechanism: These two drugs do not seem to change how much medicine stays in your system when used together.
In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased.
Mechanism: Carbamazepine makes your liver work faster to get rid of ondansetron, which lowers the amount of medicine in your body.
In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased.
Mechanism: Rifampin speeds up the breakdown of ondansetron, which can make the medicine less effective.
In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased.
Mechanism: Phenytoin causes your body to process and remove ondansetron more quickly than usual.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can I take ondansetron for morning sickness?
Does ondansetron make you sleepy?
Can I drink alcohol while taking ondansetron?
What should I do if ondansetron doesn't work?
Can I take ondansetron with other medicines?
Is ondansetron addictive?
How long does ondansetron take to work?
Can children take ondansetron?
Does food affect how ondansetron works?
Can I drive while taking ondansetron?
What are the common side effects of ondansetron?
Does ondansetron interact with other medications?
What drug class is ondansetron?
What pregnancy or breastfeeding source fields are listed for ondansetron?
Has ondansetron been recalled?
Active Recalls
Defective container: Preferred Pharmaceuticals received a letter from the manufacturer Glenmark, that the blister packs are not fully sealed and tablets falling out. Preferred Pharmaceuticals purchased the finished product and repackaged the product for sale.
Glenmark Pharmaceuticals Inc., USA
Defective container: Preferred Pharmaceuticals received a letter from the manufacturer Glenmark, that the blister packs are not fully sealed and tablets falling out. Preferred Pharmaceuticals purchased the finished product and repackaged the product for sale.
Preferred Pharmaceuticals, Inc.
Related Medications in 5-HT3 Receptor Antagonist (Antiemetic)
Other drugs grouped near ondansetron - same-class peers and common alternatives.
alosetron
Lotronex
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS).
Compare with ondansetron →
aprepitant
Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting.
Compare with ondansetron →
bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
Compare with ondansetron →
bismuth subsalicylate
Pepto-Bismol
Bismuth subsalicylate (Pepto-Bismol) is a medicine that can treat diarrhea and upset stomach.
Compare with ondansetron →
cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
Compare with ondansetron →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for ondansetron: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 103,354.
- olanzapine Δ 2 reports · Atypical Antipsychotic 103,356reports
- loratadine Δ 1,024 reports · Second-Generation Antihistamine 104,378reports
- valsartan Δ 1,048 reports · Angiotensin II Receptor Blocker (ARB) 102,306reports
- leflunomide Δ 1,259 reports · Disease-Modifying Antirheumatic Drug (DMARD) 102,095reports
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 12.99%.
- docusate Δ 0.05 pts · 55,963 reports · Stool Softener 13.04%death share
- trimethoprim Δ 0.05 pts · 11,380 reports · Dihydrofolate Reductase Inhibitor 12.93%death share
- ranolazine Δ 0.06 pts · 10,014 reports · Late Sodium Current Inhibitor (Antianginal) 12.93%death share
- paroxetine Δ 0.10 pts · 32,666 reports · Selective Serotonin Reuptake Inhibitor (SSRI) 13.09%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
Save on ondansetron
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What the FDA Data Shows for ondansetron
The FDA label for ondansetron (sold under brand names such as Zofran) classifies it as a prescription-only medication in the 5-HT3 Receptor Antagonist (Antiemetic) class. This medicine is used to prevent nausea and vomiting. Official labeling lists 4 commonly reported side effects, including Headache, Feeling tired, Constipation.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 103,354 voluntary reports. The database also lists 6 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.31.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 2 recall records on file), and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: April 24, 2024
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages