What it is
An aromatic amino acid intermediate in the biosynthesis of serotonin. Available as an oral capsule supplement in the US.
How it works
Crosses the blood-brain barrier and is decarboxylated to serotonin (5-HT), increasing central serotonergic tone. Peripheral conversion can produce gastrointestinal effects.
Where it's used
Used as a dietary supplement marketed for mood and sleep. Available as a prescription drug (Oxitriptan) in some other countries.
FDA-approved use
Regulated as a dietary supplement in the US; prescription drug in some other countries.
Tracking it
5-HTP is oral, which makes consistency the whole game — a simple daily check-off with a reminder beats memory every time. with a half-life of about 2.2 hours, a dose log also lets a tracker model the relative amount still in your system between doses.
Source
Public reference
Last reviewed 2026-06-11