Ondansetron hydrochloride: adverse event reports filed with FDA

2,330

reports as suspect product

0% of all reports · about 105 a year

255

reports, 12 months to June 2026

283 in the 12 months before

93.1%

marked serious by the reporter

86.9% across the class

14.1%

record death among outcomes, as reported

329 reports · not verified by FDA

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 hydrochloride reports recording the termmedian drug in serotonin-3 receptor antagonist

1. Off label useused for a purpose or in a way not on the label23.3%544
2. Nauseafeeling sick23.1%539
3. Drug ineffectivethe medicine did not work as expected21.8%509
4. Hyperhidrosisexcessive sweating18.7%436
5. Product use in unapproved indicationused for a purpose not on the label17.3%403
6. Painpain, site not specified16%372
7. Pyrexiafever13.4%313
8. Nightmarenightmares13.2%308
9. Sedationdrowsiness from a medicine13.1%305
10. Headachehead pain11%257
11. Nephrolithiasiskidney stones10.7%249
12. Vomitingbeing sick10.6%246
13. Fatiguetiredness10.4%242
14. Anxietyanxiety9.9%231
15. Constipationconstipation9.5%222
16. Maternal exposure during pregnancythe mother took the medicine during pregnancy7.8%182
17. Hypertensionhigh blood pressure7.6%176
18. Product use issuea problem in how the product was used7.5%175
19. Injurya physical injury7.5%174
20. Emotional distressemotional distress7.3%171
21. Foetal exposure during pregnancythe unborn baby was exposed to the medicine7.2%168
22. Dyspnoeashortness of breath6.9%160
23. Rheumatoid arthritisrheumatoid arthritis, an inflammatory joint disease6.8%159
24. Coughcough6.8%158
25. Intentional product misusedeliberate use not as intended6.8%158
26. Rashskin rash6.7%156
27. Upper respiratory tract infectiona cold or similar infection6.7%155
28. Drug intolerancethe medicine was not tolerated6.3%147
29. Psoriasispsoriasis, a skin condition5.9%138
30. Exposure during pregnancythe medicine was taken during pregnancy5.8%134

Top 30 of 913 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

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 25.5% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 2,330 reports.

Drugs most often listed in the same reports

Other products listed in reports where Ondansetron hydrochloride 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

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

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.

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 hydrochloride as a suspect or interacting product; reports listing it only as a concomitant medication (11,755) 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.