Serotonin syndrome is characterized by high levels of serotonin and symptoms like confusion, sweating, agitation, nausea, involuntary muscle contractions, and racing heartbeat. Do not take L-tryptophan if you experience these symptoms. Because tryptophan may have numerous drug interactions (most commonly, MAOIs and SSRIs) consult your healthcare provider before taking this product if you are taking prescription medications. Do not use before driving or operating heavy machinery.