I'm taking 500mg two to three times a day, depending on how many meals I have. My doctor told me to start off with one 500mg tablet a day for a week, then to build up slowly to the three tablets a day to give my body a chance to adjust to it. I've read that a lot of people have had bad side effects from them, but I can honestly say I've had none. I've been totally fine with them, and they've even brought my period back on after not having one for a long time.
I read in the information leaflet that you should consult your doctor before you stop taking them, as just suddenly stopping taking them can possibly cause side effects too. So I'd check with your doctor first.