The most commonly reported side effects of flecainide include atrial fibrillation, fatigue, and toxicity to various agents, based on 16,375 FDA adverse event reports from 2004 to 2025. 5.5% of reports found the drug to be ineffective.
Percentages show how often each reaction appears relative to total reports for flecainide.
These are voluntary reports and do not establish that flecainide caused these reactions.
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Other drugs that appear in adverse event reports alongside flecainide. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.
Also suspected
Taken alongside
Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.
55.2% of flecainide adverse event reports involve female patients and 37.3% involve male patients. The largest age group is elderly at 63%. These figures reflect who reports side effects, not underlying risk.
Sex
Age group
Conditions and purposes for which patients were taking flecainide when the adverse event was reported.
Showing 15 of 307 indications
Flecainide is sold under the brand name Flecainide Acetate.
An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.
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