Supplies L-5-Hydroxy-Tryptophan (5-HTP), the precursor to serotonin, a key neurotransmitter. 5-HTP Plus Forte supplies 150mg of 5-HTP, three times that of 5-HTP. Caution: Very high doses of 5-HTP can be metabolized peripherally, and can trigger excess serotonin formation. 5-HTP is not recommended for pregnant or lactating women, and should be avoided by those with cardiovascular disease. Additionally, 5-HTP should not be used by those taking serotonin-5-HTP, or receptor agonists (SSRIs) (naratriptan, sumatriptan, zolmitriptan).