L-5-Hydroxytryptophan L-5-Hydroxytryptophan (L-5-HTP) is a natural amino acid and dietary supplement, precursor of the neurotransmitter serotonin, and antagonist of reserpine. SKU: SLB-IH0400-1ml Supplier: Solarbio Unit: bottle Add to cart Contact Us Add to wishlist Price 127.75 € 127.75 € Terms and Conditions