Drugs › Serotonin-3 receptor antagonist
Generic name
Ondansetron: adverse event reports filed with FDA
17,524 reports list it as a suspect or interacting product, 2004–2026. Class: Serotonin-3 receptor antagonist. Also reported as Ondansetron Injectable, Ondansetron Unspecified, Ondansetron Solution For Injection.
- 17,524
- reports as suspect product
- 0.1% of all reports · about 782 a year
- 1,561
- reports, 12 months to June 2026
- 1,867 in the 12 months before
- 91.4%
- marked serious by the reporter
- 86.9% across the class
- 13.6%
- record death among outcomes, as reported
- 2,376 reports · not verified by FDA
17,524 adverse event reports received by FDA list ondansetron, a generic name as a suspect or interacting product, from February 2004 to June 2026. A further 92,949 reports list it only as a concomitant medication, and those are not counted in the figures on this page.
In the 12 months to June 2026, 1,561 reports listed it, down 16% from 1,867 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 782 reports a year and 0.1% of the 20,646,523 reports in the database, and 78.7% of the reports for the serotonin-3 receptor antagonist class. How many people take it is not in the data, so a count is not a rate of occurrence.
The MedDRA terms listed most often are nausea (10.8%), off label use (9.3%) and vomiting (8%). A report can list several reactions, so shares add to more than 100%; 2,258 different terms appear across these reports. Nausea is recorded in 10.8% of these reports, a smaller share than in the median serotonin-3 receptor antagonist drug (15.5%).
91.4% of the reports are marked serious by the reporter (86.9% across the class); 13.6% record death among the outcomes and 40.4% record hospitalisation, as reported. 40.9% of the reports came from other health professionals, and the largest patient age group is 45 to 64 (24.4%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Ondansetron reports recording the termmedian drug in serotonin-3 receptor antagonist
- Nauseafeeling sick10.8%1,885
- Off label useused for a purpose or in a way not on the label9.3%1,633
- Vomitingbeing sick8%1,398
- Drug ineffectivethe medicine did not work as expected7.9%1,391
- Pyrexiafever6.2%1,095
- Painpain, site not specified5.6%984
- Electrocardiogram QT prolongeda QT prolongation on the ECG5.6%980
- Constipationconstipation5.6%977
- Drug interactionan interaction between medicines5.2%912
- Fatiguetiredness5.2%907
- Headachehead pain4.8%839
- Maternal exposure during pregnancythe mother took the medicine during pregnancy4.7%825
- Product use in unapproved indicationused for a purpose not on the label4.6%798
- Serotonin syndrometoo much serotonin activity, with agitation, fever and tremor4.5%789
- Dyspnoeashortness of breath4.5%783
- Exposure during pregnancythe medicine was taken during pregnancy4.4%765
- Hypertensionhigh blood pressure4.2%734
- Foetal exposure during pregnancythe unborn baby was exposed to the medicine4.1%718
- Rashskin rash4%702
- Diarrhoealoose or frequent stools4%701
- Hyperhidrosisexcessive sweating3.9%686
- Abdominal painstomach or belly pain3.8%668
- Cardiac arrestthe heart stopped3.6%635
- Hypersensitivityan allergic-type reaction3.6%632
- Anxietyanxiety3.4%600
- Erythemaskin redness3.1%541
- Malaisegeneral feeling of being unwell3.1%540
- Drug hypersensitivityan allergic-type reaction to a medicine3%523
- Thrombocytopenialow platelets3%523
- Product use issuea problem in how the product was used3%517
Top 30 of 2,258 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 4 drugs in the serotonin-3 receptor antagonist class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 22,267 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 33% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Nausea | 2,209 | 12.6% |
| Prophylaxis of nausea and vomiting | 1,753 | 10% |
| Vomiting | 1,278 | 7.3% |
| Premedication | 646 | 3.7% |
| Antiemetic supportive care | 408 | 2.3% |
| Foetal exposure during pregnancy | 297 | 1.7% |
The indication field is filled in by the reporter and is often blank; shares are of all 17,524 reports.
Drugs most often listed in the same reports
| Drug (any role in the report) | Reports | Share of Ondansetron reports |
|---|---|---|
| Acetaminophen | 2,661 | 15.2% |
| Dexamethasone | 2,268 | 12.9% |
| Gabapentin | 1,658 | 9.5% |
| Metoclopramide | 1,625 | 9.3% |
| Pantoprazole | 1,332 | 7.6% |
| Methylprednisolone | 1,282 | 7.3% |
| Morphine | 1,157 | 6.6% |
| Hydromorphone | 1,130 | 6.4% |
| Furosemide | 1,072 | 6.1% |
| Propofol | 1,002 | 5.7% |
Other products listed in reports where Ondansetron is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.
In context
| Measure | Ondansetron | Serotonin-3 receptor antagonist | All reports |
|---|---|---|---|
| Reports as suspect product | 17,524 | 22,267 | 20,646,523 |
| Share of that pool | — | 78.7% | 0.1% |
| Reports, latest 12 months | 1,561 | — | 1,332,454 |
| Marked serious | 91.4% | 86.9% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 136 | 138 | 91 |
| Hospitalisation recorded, per 1,000 reports | 404 | 375 | 213 |
| Consumer-filed share | 13.8% | 15.2% | 45.8% |
| Top term, share of reports | Nausea 10.8% | median 15.5% | 3.8% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the serotonin-3 receptor antagonist class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Ondansetron hydrochloride | generic | 2,330 | 255 | 93.1% |
| Granisetron | generic | 1,246 | 51 | 61.4% |
| Sancuso | brand | 1,167 | 0 | 33.5% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Ondansetron reports
How many adverse event reports has FDA received for Ondansetron?
17,524 reports list Ondansetron as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 1,561 of them arrived in the latest 12 months. Another 92,949 list it only as a concomitant medication.
What reactions are recorded in Ondansetron reports?
nausea (10.8%), off label use (9.3%), vomiting (8%), drug ineffective (7.9%) and pyrexia (6.2%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Ondansetron was responsible.
How serious are the reports?
91.4% are marked serious by the reporter. Among the outcomes recorded, 13.6% of reports include death and 40.4% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
other health professional (40.9%), physician (30.6%) and consumer or non-health professional (13.8%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Ondansetron rising?
1,561 reports in the 12 months to June 2026, down 16% from 1,867 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Ondansetron was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Ondansetron?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Ondansetron as a suspect or interacting product; reports listing it only as a concomitant medication (92,949) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.