5-HTP in a nutshell by Cinogen:

What is it? A serotonin precursor.
Where can you get it? Walmart.
What's it cost? $8.
How do you use it? Ingest 2 - 5 pills .5 - 1 hour before smoking.
What will it do? Generate a more active, vibrant high.
Any dangers? Taking too many pills can cause vomiting. Effects of overdose can include serotonin syndrome in select individuals.

That's about all.

-Cin