a day for high blood pressure. My question is; do side effects usually occur within the first couple of days of taking a new medication, or does the drug have to build up in your system before you notice something? So far, I've had great success while taking Flecainide. I had several episodes of atrial flutter that were bad enough to send me to the ER twice. Each time, several tests were performed only to have the doctor tell me that my heart was normal. I have had episodes ever since I was in my last trimester of pregnancy-171/2 years ago! There were times that I could only walk 5 or 6 steps and my heart would "drop" and then flutter. It was very annoying. I am very optimistic with this drug, I hope the "honeymoon" period lasts!