You can go up to about 200 - 300 mcg. I used to take 2 150 mcg drops of selenium a day, you can lessen it depending on what reactions you have. YOu should also take it seperately from vitamin C (about 2 hours apart), because it can "apparently" interfere with the uptake of it. Not sure if that's absolutely true or not, but I'd do it anyway just to be sure.