I've supplemented with a little L-tyrosine for some years now. It certainly didn't prevent the rise in prolactin. I'd be cautious with 5-HTP. Even too much of its precursor, L-tryptophan, gave me problems that in hindsight were from higher prolactin. The chain is L-tryptophan -> 5-HTP -> serotonin. And "Serotonin potently increases prolactin and there is a very good correlation between prolactin and serotonin."[
R] Furthermore, taking 5-HTP bypasses an upstream rate-limiting step, making it easier to overdose.