I've been taking it for three years to great and wonderful effect. Today I experienced nine episodes of nausea, weakness to the point where I had to immediately sit down, and one fainting spell where I fell from my chair and hit my head on two or three objects on the way down. The doctor said I had low sodium today. I increased salt ingestion, but have had four more episodes since the visit. They seemed a bit shorter and I didn't faint, but I still had them after filling up on sodium. I know Flecainide affects sodium levels but after much research am still not sure if it decreases them. I am 64 and have discovered that men in my age group are more likely to have fainting spells, but can't find if it also decreases sodium. If anyone can answer this question, I'd be beholden.