✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
📰Read the full L-Tryptophan evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ SSRIs/MAOIs + tryptophan = SEROTONIN SYNDROME risk [1]
⚠ 1989 EMS was contamination, not tryptophan toxicity [2]
⚠ 5-HTP is more efficient for serotonin (bypasses rate-limiting step) [1]
⚠ Turkey sleepiness myth debunked [1]
ℹ️ Not obtained from food. Obtained as part of dietary protein rather than tracked individually toward a daily target.
🔬 Lab interpreter
ℹ️ No validated blood test. There is no established laboratory test to assess status or guide dosing for this ingredient. Clinical response and symptoms are the practical guide.
⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Essential amino acid. Supplemental: limited data [1].
👦 Pediatric: See guidance
Essential nutrient from food [1].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Bedtime (sleep) or divided (mood). Empty stomach [1].
💊 With food: EMPTY stomach — LNAAs compete for brain transporter [1].
🚫 Avoid: SSRIs. MAOIs. Triptans [1].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['L-Tryptophan capsules', 'common', '500–1,000 mg per capsule [1].'] | Standard | Check label | |
| ['5-HTP (alternative)', '', 'Downstream metabolite. Bypasses rate-limiting step. See 5-HTP entry [1].'] | Standard | Check label |
3 Common questions
Is tryptophan safe after the 1989 scare? ▼
The EMS outbreak was definitively traced to a contaminated batch from one manufacturer (Showa Denko). Tryptophan itself is safe when properly manufactured. The FDA lifted the ban in 2005. Modern products are safe [2].
Tryptophan vs 5-HTP? ▼
Both increase serotonin. 5-HTP bypasses the rate-limiting step (tryptophan hydroxylase) and is more direct. Tryptophan is upstream and also feeds other pathways (kynurenine, niacin). For pure serotonin: 5-HTP. For broader metabolism: tryptophan [1].
Does turkey make you sleepy? ▼
No more than chicken — turkey has similar tryptophan content. Post-Thanksgiving drowsiness is from overeating, alcohol, and high carbohydrate intake (which actually does help tryptophan cross the BBB by reducing LNAA competition) [1].
4 Clinical evidence
Strong
Tryptophan → serotonin → melatonin pathway: established biochemistry [1]. 1989 EMS: definitively traced to contamination, not tryptophan itself [2]. HIGH
Moderate
Sleep: some positive trials for sleep latency reduction at 1–2 g [1]. Mood: tryptophan depletion studies confirm serotonin link to mood [1]. Premenstrual irritability: one trial positive [1]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Absolute contraindications
✕ Concurrent MAOIs — serotonin syndrome/hypertensive risk
Relative
⚠ Concurrent SSRIs/SNRIs/triptans — serotonin syndrome
⚠ History of eosinophilia-myalgia concern (contaminant-related) — use pharmaceutical-grade
⚠ Carcinoid syndrome
⚠ Sedation — caution when driving
🚩 Red flags
● SSRI/MAOI patient + tryptophan — serotonin syndrome [1]
● Patient worried about 1989 EMS — explain contamination, not inherent toxicity [2]
6 Interactions
Drug interactions
SSRIs/SNRIs/MAOIs Major
Mechanism: Additive serotonin. [1]
Effect: Serotonin syndrome (hyperthermia, agitation, clonus, autonomic instability). [1]
Action: AVOID combination without specialist guidance [1].
Triptans Major
Mechanism: Additive serotonergic. [1]
Effect: Serotonin syndrome risk. [1]
Action: Avoid [1].
Supplement synergies
Vitamin B6 (P5P) · 25–50 mg P5P
B6 is cofactor for tryptophan → serotonin conversion [1].
B6 is cofactor for tryptophan → serotonin conversion [1].
Magnesium · 200–400 mg Mg glycinate
Supports serotonin receptor function [1].
Supports serotonin receptor function [1].
7 Regulatory
United States (FDA): Dietary supplement (re-authorized 2005 after 1989–2005 ban) [2].
8 US supplement products
9
on-market products containing L-Tryptophan (NIH DSLD)
Brands carrying L-Tryptophan (2)
Click a brand to see its L-Tryptophan products.
9 Frequently paired with
10 Cite this page
Vancouver: Pkhakadze G. L-Tryptophan — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/l-tryptophan/
APA 7th: Pkhakadze, G. (2026). L-Tryptophan — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/l-tryptophan/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 2 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "L-Tryptophan — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/l-tryptophan/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG