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5-HTP / L-Tryptophan

Evidence: ★★★☆☆ · Status: OTC Supplement

💡 Did you know? 5-HTP is a direct serotonin precursor — which is exactly why combining it with an antidepressant can be dangerous, not helpful.

In plain English

Raw material for serotonin (mood/sleep). Useful, but don't combine with antidepressants (serotonin syndrome), and take with B6.

How it works

Direct precursors to serotonin (5-HTP bypasses the rate-limiting step); tryptophan also → melatonin.

Molecular target & official sources

TPH2 tryptophan hydroxylase (NCBI Gene) · 5-HTP (PubChem CID 144)

Watch out

Never with SSRIs/MAOIs. Cycle to avoid depleting dopamine.

Bottom line

Effective for mood/sleep alone; dangerous with serotonergic drugs.

Helps with: Sleep Better · Stress & Anxiety

Stacks with

Shares a pathway — often paired with: Caffeine, Modafinil / Armodafinil, Amphetamine (Adderall) / Lisdexamfetamine (Vyvanse), Methylphenidate (Ritalin).

Availability & where to buy

Available over the counter. Widely available OTC — e.g. iHerb (ships worldwide); in Singapore also Guardian, Watsons, GNC, Shopee / Lazada. Look for a third-party-tested / GMP mark and check the dose per serving.

How it works: the Monoamines pathway →

Used in these protocols

Low Mood / Depression

Common questions

Does 5-HTP / L-Tryptophan actually work?

Human-evidence rating: 3 of 5. Effective for mood/sleep alone; dangerous with serotonergic drugs.

What are the risks or side effects of 5-HTP / L-Tryptophan?

Never with SSRIs/MAOIs. Cycle to avoid depleting dopamine.

Is 5-HTP / L-Tryptophan legal or approved?

Regulatory status: OTC Supplement.