I take 1200 mg a day with no side effects! It worked quickly for me!! Saw amazing results fast. Started using it mid cycle because I had been ovulating on cd28 prior to using vitex. Started taking it on cd18 last month and ovulated cd21! Three days after starting it!! My cycle was 2 days less last month too. Usually it's 35 days long with only one week of LP. So I strongly recommend for irregular cycles !! 1000mg or more for the first 3 months. Then you can lower the dose if you want but not necessary. And take it the whole month. It won't work just taking it half ur cycle..