5-HTP
Over the last two years since I have been effectively treating depression, anxiety, and a variety of other emotional and physical disorders with 5-HTP, and because so many patients are on SSRI antidepressant medications when they come in to see me, I am frequently asked about the chances of the patient developing “serotonin syndrome” (SS) that results from excess serotonin in the central nervous system. Classically this has been seen when certain drugs (like MAOI antidepressants) are combined with SSRI medications. The signs and symptoms of SS are euphoria, drowsiness, sustained rapid eye movement, overreaction of the reflexes, rapid muscle contraction and relaxation in the ankle causing abnormal movements of the foot, clumsiness, restlessness, feeling drunk and dizzy, muscle contraction and relaxation in the jaw, sweating, intoxication, muscle twitching, rigidity, high body temperature, mental status changes were frequent (including confusion and hypomania - a "happy drunk" state), shivering, diarrhea, loss of consciousness and death. Since 5HTP can directly increase serotonin levels, this patient concern is deserving of a careful answer.

So far, the vast majority of the cases of SS described in the literature have resulted from combined pharmaceuticals. However there have been some instances occurring soon after the start of a single SSRI drug. There have been no instances (reference a study published in Toxicology Letters performed at ISSI Labs, Inc) of SS described in the last twenty years that were proven to result from the combined use of SSRI’s and 5HTP, or from 5HTP alone. This is particularly significant because the clinicians that are leading the way with the use of 5HTP as the ideal therapy for conditions associated with low serotonin have been using doses up to and even exceeding 600 mg per day. My experience is the same. 5HTP can occasionally cause some stomach upset, but I have never seen the SS in any patient over my 30 years of clinical practice. Occasionally someone will ask if 5HTP is the same as L-trytophan, which was associated with some toxicity in the mid eighties due to manufacturing contamination causing eosinophilic myalgia syndrome. It is not the same, and it has never been found to be contaminated with “peak X” like L-tryptophan.

Although 5HTP is a marvelous, effective, and very safe therapeutic agent for patients with neurotransmitter related diseases, it should be used under a knowledgeable physician’s supervision, and with periodic testing of urinary levels reflecting serotonin excretion. The SS should never-the-less always be kept in mind by the careful physician as a theoretical though very low likelihood possibility whenever therapy affecting serotonergic neurons is attempted. When it does occur and the SS is quickly and correctly  diagnosed, immediate discontinuation of the offending agent leads to prompt resolution usually within 24 hours.