Quick Comparison
| 5-HTP | Fasoracetam | |
|---|---|---|
| Half-Life | 2-5 hours | 1.5-2.5 hours |
| Typical Dosage | Standard: 50-200 mg daily. For mood: 50-100 mg 2-3 times daily. For sleep: 100-300 mg 30-60 minutes before bed. Start low — some people are very sensitive. Take with food to reduce nausea. | Standard: 20-100 mg sublingually or orally, 1-3 times daily. Many users find 20-40 mg effective. Clinical trials for ADHD used 100-400 mg twice daily. |
| Administration | Oral (capsules, tablets). Take with food to reduce GI side effects. Evening dosing preferred for sleep benefits. | Oral or sublingual. Sublingual may provide better absorption. |
| Research Papers | 10 papers | 5 papers |
| Categories |
Mechanism of Action
5-HTP
5-HTP readily crosses the blood-brain barrier via the large neutral amino acid transporter (LAT1/SLC7A5), unlike serotonin itself which cannot. Once in the brain, aromatic L-amino acid decarboxylase (AADC, also called DOPA decarboxylase) converts 5-HTP to serotonin (5-hydroxytryptamine) using pyridoxal-5-phosphate (active vitamin B6) as a cofactor. This completely bypasses tryptophan hydroxylase (TPH2), the rate-limiting enzyme in the normal serotonin synthesis pathway from dietary L-tryptophan. The result is a reliable, dose-dependent increase in serotonin across multiple brain regions including the dorsal raphe nucleus, hippocampus, and prefrontal cortex. Elevated serotonin activates 5-HT1A autoreceptors (calming), 5-HT2A/2C postsynaptic receptors (mood modulation), and 5-HT3 receptors (gut-brain signaling). In the pineal gland, serotonin is converted by arylalkylamine N-acetyltransferase (AANAT) to N-acetylserotonin, then by hydroxyindole O-methyltransferase (HIOMT) to melatonin — explaining the sleep-promoting effects.
Fasoracetam
Fasoracetam upregulates GABA-B receptor (GABA-B1/GABA-B2 heterodimer) expression and function, which is unique among racetams — this receptor upregulation is potentially beneficial for restoring GABAergic sensitivity after prolonged benzodiazepine or phenibut use. It enhances group II metabotropic glutamate receptor (mGluR2/mGluR3) signaling, which modulates presynaptic glutamate release and reduces excitotoxicity. Fasoracetam increases acetylcholine release in the cerebral cortex via modulation of choline acetyltransferase activity and vesicular acetylcholine transporter function. It may also modulate the glutamatergic system through mGluR5. The combination of GABAergic (GABA-B-mediated inhibition), glutamatergic (mGluR modulation), and cholinergic enhancement provides anxiolytic effects alongside cognitive enhancement. Clinical trials focus on ADHD patients with GRM (glutamate receptor) gene variants.
Risks & Safety
5-HTP
Common
Nausea, diarrhea, stomach cramps.
Serious
Serotonin syndrome when combined with SSRIs, SNRIs, MAOIs, or tramadol — DO NOT combine without medical supervision.
Rare
Eosinophilia-myalgia syndrome (historical concern from contaminated L-tryptophan, not confirmed with modern 5-HTP).
Fasoracetam
Common
Headache, fatigue, mild digestive discomfort.
Serious
Limited long-term human safety data.
Rare
Low mood, brain fog, loss of motivation at very high doses.
Full Profiles
5-HTP →
5-Hydroxytryptophan is the immediate precursor to serotonin, derived from the seeds of Griffonia simplicifolia. By providing the rate-limiting intermediate in serotonin synthesis, 5-HTP effectively raises brain serotonin levels. Used for mood support, anxiety, sleep, and appetite control. More effective than L-Tryptophan because it bypasses the rate-limiting enzyme step.
Fasoracetam →
A newer racetam that uniquely upregulates GABA-B receptors, making it potentially useful for people who have developed tolerance to GABAergic substances like Phenibut or benzodiazepines. It also enhances glutamate and acetylcholine signaling. Being studied in clinical trials for ADHD in adolescents with specific glutamate receptor gene mutations.