Flecainide acetate: adverse event reports filed with FDA

1,447

reports as suspect product

0% of all reports · about 64 a year

78

reports, 12 months to June 2026

100 in the 12 months before

87.6%

marked serious by the reporter

73.5% across the class

13.6%

record death among outcomes, as reported

197 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 Flecainide acetate reports recording the termmedian drug in antiarrhythmic

1. Toxicity to various agentspoisoning or toxic effect of one or more substances11.7%170
2. Drug interactionan interaction between medicines7.7%111
3. Electrocardiogram QRS complex prolonged7.6%110
4. Atrial fibrillationan irregular heart rhythm7.3%106
5. Hypotensionlow blood pressure7.3%106
6. Bradycardiaslow heart rate5.8%84
7. Electrocardiogram QT prolongeda QT prolongation on the ECG5.5%80
8. Ventricular tachycardiaa fast rhythm from the lower heart chambers5%73
9. Drug ineffectivethe medicine did not work as expected5%72
10. Cardiac arrestthe heart stopped4.7%68
11. Dyspnoeashortness of breath4.6%67
12. Tachycardiafast heart rate4.4%63
13. Overdosea dose above the recommended amount4.2%61
14. Completed suicidedeath by suicide3.3%48
15. Dizzinesslight-headedness or unsteadiness3.2%47
16. Nauseafeeling sick3.2%47
17. Syncopefainting3.2%47
18. Intentional overdosea deliberate overdose3%44
19. Malaisegeneral feeling of being unwell3%44
20. Loss of consciousnesspassing out2.6%38
21. Cardiogenic shockshock from the heart failing to pump2.6%37
22. Atrial flutter2.4%35
23. Electrocardiogram abnormal2.4%35
24. Astheniaweakness or lack of energy2.3%33
25. Hyponatraemialow blood sodium2.3%33
26. Arrhythmia2.1%31
27. Cardio-respiratory arrestthe heart and breathing stopped2.1%31
28. Interstitial lung diseasescarring or inflammation of lung tissue2.1%31
29. Vomitingbeing sick2.1%31
30. Falla fall2.1%30

Top 30 of 404 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 11 drugs in the antiarrhythmic 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 30,807 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. 48.6% 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 1,447 reports.

Drugs most often listed in the same reports

Other products listed in reports where Flecainide acetate 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 antiarrhythmic 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 Flecainide acetate as a suspect or interacting product; reports listing it only as a concomitant medication (3,843) 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.