Are there any studies where 5-HTP was compared directly to antidepressant drugs?

Are there any studies where 5-HTP was compared directly to antidepressant drugs?
Yes, there are several. 5-HTP is equal to or better than standard antidepressant drugs and the side effects are much less severe. The study with the most significance was one that compared to fluvoxamine, a "selective serotonin re-uptake inhibitor" like Prozac, Paxil, and Zoloft. In the study, subjects received either 5-HTP (100 mg) or fluvoxamine (50 mg) three times daily for 6 weeks (5). The percentage decrease in overall depression scores was slightly better in the 5-HTP group (60.7% vs. 56.1%). More patients responded to 5-HTP than fluvoxamine and 5-HTP was quicker acting than the fluvoxamine.

The real advantage of 5-HTP in this study was the low rate of side effect. Here is how the physicians described the differences among the two groups:

"Whereas the two treatment groups did not differ significantly in the number of patients sustaining adverse events, the interaction between the degree of severity and the type of medication was highly significant: fluvoxamine predominantly produced moderate to severe, oxitriptan [5-HTP] primarily mild forms of adverse effects."

The most common side effects with 5-HTP were nausea, heartburn, and gastrointestinal problems (flatulence, feelings of fullness, and rumbling sensations). These side effects were rated as being very mild to mild. In contrast, most of the side effects experienced in the fluvoxamine group were of moderate to severe intensity.