I'm willing to accept that using 5-HTP only works for some people. This could quite reasonably be the case, given the scope for diversity in each individual's physiology (genetic polymorphisms, varying levels of the various enzymes involved in the manufacture of serotonin, etc.).
I'm only pointing this out because I have seen reviews on the internet where people swear 5-HTP doesn't work. The fact is, for me, it has an EXTREMELY pronounced effect - mydriasis, increased libido, not to mention the mood alteration. That sure as hell isn't down to the placebo effect.
I guess the take home message here is these tablets, and 5-HTP "supplements" in general, are NOT to be taken lightly! An accidental overdose has the potential to put you in hospital or even kill you, and if you are on ANY psychiatric medications then please, steer well clear until you've consulted your GP. SSRIs in particular can easily be fatal in combination with 5-HTP due to an extended 'overdose' of serotonin. Side note: If you're sweating a lot more than normal, you have probably taken too much.
That aside, these tablets gave me an almost instantaneous lift out of SAD/atypical depression and I can't emphasise enough how grateful I am for that. They might even be too strong for some people - I'd recommend just one tablet, at around 7pm, to minimise the risk of any possible side effects interfering with your day/night. I may actually have to purchase some 50mg tablets in order to spread this dose out.
In summary: Definitely worth a try. Be careful. Be sensible!