People have taken upto 50g a day (this is very expensive). 18g was used in the most well known study - the Israeli study. Between 4g and 18g works for most. I use around 5g - sometimes 8g... together with 5HTP. I have also been using St. Johns Wort - but I may drop it.. I am unsure as to whether it helps. BTW I have bouts of anxiety and depression. Inositol and 5HTP help alot and more than any anti-dep I have ever tried (Efexor, Lustral, Prozac).
I don't know why it causes water problems in Sonny.... maybe he has a unique reaction to the vitamin.