Is 5-HTP (5-Hydroxytryptophan) Safe with Monoamine Oxidase Inhibitors (MAOIs)?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Never combine MAOIs (e.g., phenelzine, tranylcypromine, selegiline) with 5-HTP supplements. This combination is contraindicated. Ensure a washout period of at least 14 days after stopping an MAOI before any serotonergic supplement is considered.
Why this interaction occurs
MAOIs inhibit the breakdown of serotonin by monoamine oxidase, while 5-HTP increases serotonin production. Together, they cause a dramatic accumulation of serotonin leading to serotonin syndrome. Animal models using tranylcypromine (an MAOI) and 5-HTP confirmed exaggerated serotonin syndrome behaviors in SERT-deficient mice, modeling the human risk.
Evidence
Evidence level: moderate.
Data source
PubMed - PMID 19275775
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 5,667,546 reports mentioning Monoamine Oxidase Inhibitors (MAOIs). This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Monoamine Oxidase Inhibitors (MAOIs) + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All 5-HTP (5-Hydroxytryptophan) interactions → · All Monoamine Oxidase Inhibitors (MAOIs) interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.