Sulfamethoxazole and trimethoprim: adverse event reports filed with FDA

9,070

reports as suspect product

0% of all reports · about 403 a year

402

reports, 12 months to June 2026

679 in the 12 months before

87.6%

marked serious by the reporter

89.3% across the class

18.5%

record death among outcomes, as reported

1,679 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 Sulfamethoxazole and trimethoprim reports recording the termmedian drug in dihydrofolate reductase inhibitor antibacterial

1. Rashskin rash19.2%1,738
2. Pyrexiafever17%1,544
3. Drug ineffectivethe medicine did not work as expected16.1%1,457
4. Pruritusitching15.5%1,403
5. Fatiguetiredness14.2%1,285
6. Dyspnoeashortness of breath14.1%1,279
7. Joint swellinga swollen joint13.8%1,250
8. Painpain, site not specified13.6%1,235
9. Hypersensitivityan allergic-type reaction13.6%1,234
10. Sinusitissinus infection13.3%1,203
11. Peripheral swellingswelling of the arms or legs12.9%1,173
12. Lower respiratory tract infectiona chest infection12.8%1,162
13. Infectionan infection, type not specified12.8%1,159
14. Stomatitissore mouth12.6%1,142
15. Swellingswelling12.6%1,140
16. Folliculitis12.5%1,138
17. Impaired healingslow healing12.3%1,120
18. Confusional stateconfusion12.2%1,103
19. Gastrointestinal disorder12.1%1,099
20. Arthralgiajoint pain12.1%1,098
21. Weight increasedweight gain12.1%1,097
22. Irritable bowel syndrome12.1%1,095
23. Blistera blister12.1%1,094
24. Nasopharyngitisa cold11.5%1,042
25. Muscle injury11.4%1,032
26. Drug hypersensitivityan allergic-type reaction to a medicine10.8%978
27. Ill-defined disordera condition that was not clearly described10.5%952
28. Sleep disorder due to general medical condition, insomnia type9.6%874
29. Vomitingbeing sick9.6%872
30. Infusion related reactiona reaction during or soon after an infusion9.5%862

Top 30 of 1,262 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 6 drugs in the dihydrofolate reductase inhibitor antibacterial 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 41,847 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. 43.4% 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 9,070 reports.

Drugs most often listed in the same reports

Other products listed in reports where Sulfamethoxazole and trimethoprim 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 dihydrofolate reductase inhibitor antibacterial 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 Sulfamethoxazole and trimethoprim as a suspect or interacting product; reports listing it only as a concomitant medication (10,633) 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.