I've been using 5-HTP whenever I feel I need it for about 4 years now. At that time, I was stuck with a doctor who really didn't understand PTSD and thought that my depression and anxiety were not only unrelated, but contradictory. To make a long story short, I abruptly stopped seeing her and taking the SSRIs she had prescribed me, because she wouldn't listen to me. She wouldn't prescribe the same combination I had used and had success with while seeing my original doctor (retired). I figured that getting through this on my own / using natural supplements had to be better than putting up with this doctor's backwards thinking.
I really don't recommend doing what I did - don't abruptly replace other medication with 5-HTP. I've never felt more physically ill in my life than I did that week! That being said, I do really feel that 5-HTP has helped me a lot. I've managed to stay off prescription antidepressants for 4 years now, and though I don't feel that my depression has ever been completely gone in that time, I also haven't had any lengthy bad periods.