Flecainide-induced hyponatremia has not been reported.
In this case report, hyponatremia was precipitated by flecainide
and subsided after stopping the flecainide. We postulate
that the mechanism is flecainide’s direct inhibition
of renal and intestinal epithelial sodium channels, leading
to the reduction of sodium absorption and, subsequently, to
hyponatremia. Further investigation is needed to define the
mechanism underlying this finding.