200mgs. of 5HTP a day caused me anorgasmia. That was a while back, haven't used it since for that very reason but I did find it very effective for my insomnia and depression.
Agonism of 5-ht2c receptors is suspected to be the main culprit behind anorgasmia.
My libido however was fine, maybe even a little better due to a decrease in my anxiety and improvement in my mood. Just couldn't cum for shit.