This site recommends that you take it UNDER THE GUIDANCE OF A PHYSICIAN:
http://depression.about.com/cs/altmed5htp/f/5htp.htm

Irrational thoughts for any significant period of time need to be addressed with a professional. It can be related to something as simple as a malfunctioning thyroid. It can of course also be depression.

PM me if you would like to hear my story. I have never regretted getting help.
Mary