I take 20mg of Prozac a day (but my doctor STARTED me on this dosage, not the 10mg) and haven't had any heart palpitations, but I do get dizzy pretty easily. I've been dizzy for a WHILE though, not just from the Prozac. I just think I get that way on my own even without it, and yes, sometimes I feel like I will faint. I just try to not get up too quickly after sitting or laying down, stay very well hydrated, and I watch what I eat. Certain fooRAB seem to make me feel worse. If it's really causing a lot of trouble, I'd definitely talk to your doctor about it though! Good luck!