As lagoya mentioned, you may or may not experience side effects. If so, they range from annoying side effects to serious side effects. If it's helpful, when I took flecainide, I had weird dreams, shakiness, tremors and gastointestinal problems. It wasn't horrible, but it was bothersome enough that the doctor switched me to rhythmol.
Great suggestion from lagoya on checing out the medication under "Health Topics" above.