In their 2006 meta-analysis cited above, Turner and colleagues concluded that 5-HTP
supplementation deserves reconsideration as an anti-depressant, but that it is
premature to recommend its widespread clinical use until more extensive clinical trials
further address its efficacy and safety, especially in adjunctive use with SSRIs.
Iovieno et al. concur, stating that in the absence of any studies of modern anti-
depressants, 5-HTP should be “used with caution” as an adjunct to SSRI or MAOI
treatment (due to the risk of serotonin syndrome) and that “vigilance” is necessary if
5 - HTP is used in monotherapy or adjunctive treatment with tricyclics.
Brown et al. II, through Akhondzadeh, Gerbarg, P.L. and Brown, R.P., reviewed 27
studies of 5-HTP treatment for depression and found only five showed statistically
significant results over placebo. They conclude that, “limited evidence supports the
use of 5-HTP as augmentation to antidepressant medications.”^6
There are no adequate, well-controlled trials on the use of 5 - HTP or tryptophan in
children or in pregnant or lactating women, nor any systematic studies evaluating long-
term side effects.
- SUGGESTED BUT UNPROVEN USES: FIBROMYALGIA, INSOMNIA, BINGE EATING
ASSOCIATED WITH OBESITY, CEREBELLAR ATAXIA, AND CHRONIC HEADACHES: According
to Iovieno et al., 5-HTP has been used clinically for over 30 years for the treatment of a
wide variety of conditions, including fibromyalgia, insomnia, binge eating associated with
obesity, cerebellar ataxia, and chronic headaches. There are no published studies of these
uses, with the exception of Lake and Spiegel’s reference to insomnia treatment. Lake and
Spiegel state that, “doses up to 600 mg have been shown to be effective in treating
insomnia but may increase the incidence of vivid dreams.”^7 They recommend 100-300 mg
30 - 45 minutes before bedtime for insomnia.
- DRUG INTERACTIONS: There is concern about the possibility that combining tryptophan or
5 - HTP with any psychotropic drug, especially an MAOI or SSRI antidepressant, may cause
serotonin syndrome. This syndrome is characterized by hypertension, hyperthermia,
