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Dietary supplement

100% Pure L-Tryptophan 500 Milligrams Ingredients & Drug Interactions

by NutraBio

100% Pure L-Tryptophan 500 Milligrams label
See full label image
Capsule Category: Amino Acid/protein
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking 100% Pure L-Tryptophan 500 Milligrams against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

100% Pure L-Tryptophan 500 Milligrams is a dietary supplement by NutraBio with 1 active ingredient. Its ingredients are commonly taken for sleep problems, low mood and depression, anxiety.Based on those ingredients, 394 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are L-Tryptophan. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against 100% Pure L-Tryptophan 500 Milligrams by NutraBio

Ask about any prescription or over-the-counter medication and we check it for interactions with 100% Pure L-Tryptophan 500 Milligrams by NutraBio — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of 100% Pure L-Tryptophan 500 Milligrams by NutraBio

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: L-Tryptophan 500 milligrams per capsule. L-Tryptophan is an amino acid your body uses to make serotonin, a brain chemical involved in mood, sleep, and other functions.

The capsule itself is made from vegetable material.

Does it work?

Couldn't assess
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

This is a single-ingredient L-tryptophan product and its label doesn't state a use — see L-tryptophan's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The evidence for L-Tryptophan's effectiveness is mixed and limited. For depression, the data shows it is possibly ineffective.

For anxiety, bruxism (teeth grinding), athletic performance, and premenstrual dysphoric disorder (PMDD), we don't have enough reliable evidence to say whether it works or doesn't. If you're considering it for any of these uses, talk with your pharmacist or doctor about what the current research actually supports.

The evidence, ingredient by ingredient L-tryptophan

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-Tryptophan is generally well tolerated when taken by mouth, but common side effects include belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting. There is a past safety concern you should know about: in 1989, a contaminated batch of L-Tryptophan from a Japanese manufacturer caused over 1,500 cases of a serious neurological disorder called eosinophilia-myalgia syndrome (EMS), with symptoms including skin changes, hair loss, and rash.

About 95% of those cases traced back to that one contaminated source. The product was recalled in the U.S. in 1990.

Modern L-Tryptophan products are not thought to carry that same risk, but the history is important context. Regarding pregnancy, safety data is conflicting — some evidence suggests it may be unsafe, so it's best avoided.

While breastfeeding, safety is not established, so avoid it unless your doctor advises otherwise.

Side effects, ingredient by ingredient L-tryptophan

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — L-tryptophan.
  • The most serious interaction on file is rated Major.
  • For scale: 394 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check before taking this if you're on CNS depressants (sleeping pills, sedatives, anxiety medications, opioids, or alcohol) — risk of excessive drowsiness is Major. Also check serotonergic drugs like antidepressants (SSRIs, SNRIs) and certain migraine medications — risk of serotonin syndrome is Moderate.

Use the medication checker on this page to verify your exact prescriptions.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Major medication interactions have been identified, and safety information is well characterized.

L-Tryptophan may appeal to people interested in natural mood or sleep support, but the evidence for those uses is weak or absent. Anyone taking sedatives, sleeping pills, anxiety medications, or antidepressants needs to check with their pharmacist first — the interaction risks are real.

The historical contamination scare is old news, but it's worth knowing your product comes from a reputable source.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Oct 22, 2015.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about 100% Pure L-Tryptophan 500 Milligrams, straight from the product label.

Brand NutraBio
Barcode (UPC) 649908235567
Net contents 150 Cap(s)
Market status On market
Date entered into DSLD Oct 22, 2015
DSLD ID 51197
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Kosher, No Allergies, Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for 100% Pure L-Tryptophan 500 Milligrams by NutraBio, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Vegetable Capsule(s)
Maximum serving Sizes:
2 Vegetable Capsule(s)
Servings per container
150
UPC/BARCODE
649908235567
IngredientAmount% DV
L-Tryptophan500 mg--

Other ingredients: Vegetable Capsule

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

1-2 capsule(s) - 1-2x daily - Best if taken empty stomach Suggested Use: As a dietary supplement, 1-2 capsules on an empty stomach, 1-2 times daily, or as directed by your physician. For maximum benefit, take up to 3 grams per day. As a sleep aid, take 1-3 capsules 30 minutes before bedtime, during the night if required, or as needed.

Formulation

- Allergen free - Non-GMO - Ggluten free - BSE/TSE free

Vegeterian

- No fillers - No excipients - No additives Free of harmful impurities.

Kosher, Vegetarian, Hypoallergenic, Non-GMO, Gluten free and BSE/TSE free. No added sugars, salt, preservatives, salicylates, or artificial color, flavor or fragrance.

Kosher, Vegetarian, Hypoallergenic, Non-GMO, Gluten free and BSE/TSE free.

Formula

- Allergen free

Kosher, Vegetarian, Hypoallergenic, Non-GMO, Gluten free and BSE/TSE free.

Kosher, Vegetarian, Hypoallergenic, Non-GMO, Gluten free and BSE/TSE free.

Precautions

Warning: Not Intended for use by persons under the age of 18. Keep out of the reach of children.

If you are pregnant, breast feeding, have known medical conditions (including kidney or liver disease) or are taking prescription or OTC medication(s) consult with your health care practitioner before using this product. Caution!: If you are currently taking, or within the last 90 days have taken, any anti-stress, anti-anxiety, or anti-depression medications do not take L-Tryptophan without first talking to your prescribing physician.

General Statements

Manufactured in a GMP & FDA inspected facility

Made in a GMP & FDA inspected facility

Free form amino acid

Pharmaceutical grade. HPLC lab tested for potency.

150 servings 500 milligrams

Since 1996

Made in USA

Vegetable Capsule

Brand IP Statement(s)

Amino Therapy

Seals/Symbols

TRUE LABEL FULL LABEL DISCLOSURE

OU

FDA Statement of Identity

Dietary Supplement

Storage

Store in a cool dry place.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration.This product is not intended to diagnose, treat, cure or prevent any disease.

General

23556-004 B20035-03

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

100% Pure L-Tryptophan 500 Milligrams by NutraBio label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

100% Pure L-Tryptophan 500 Milligrams label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in 100% Pure L-Tryptophan 500 Milligrams by NutraBio

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Vegetable Capsule(s) Dosage formCapsule Servings per container150 Amounts shown are per serving.

L-Tryptophan

Interacts with
394 drugs
500 mg per serving

L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for...

L-Tryptophan monograph & interactions

Other (inactive) ingredients: Vegetable Capsule. These complete the product’s ingredient list but are not active constituents.

Interaction report

100% Pure L-Tryptophan 500 Milligrams by NutraBio Drug Interactions

Want to check YOUR meds against 100% Pure L-Tryptophan 500 Milligrams?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
394Drugs
248 Major 146 Moderate

Ingredients driving the most interactions

L-Tryptophan 394

Individual Drug Interactions

The ingredients in 100% Pure L-Tryptophan 500 Milligrams interact with 394 drugs. Click any drug to see the details.

1 of the 1 ingredient in 100% Pure L-Tryptophan 500 Milligrams interact with drugs. Each result below shows which ingredient is responsible. L-Tryptophan

Each ingredient & the kinds of drugs it affects

For each ingredient in 100% Pure L-Tryptophan 500 Milligrams with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

L-Tryptophan2 drug types · 394 drugs

Cns Depressants

Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.
Clinical research shows that L-tryptophan can cause fatigue and drowsiness.

Likelihood Probable Evidence B
Serotonergic Drugs

Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.
L-tryptophan is a precursor to serotonin. Theoretically, combining serotonergic drugs with L-tryptophan might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.

Likelihood Possible Evidence D
L-Tryptophan full monograph & interactions
The maker

Brand information

Manufacturer and brand details for 100% Pure L-Tryptophan 500 Milligrams, from the product label.

NutraBio

See all NutraBio products
Name
NutraBio Labs, Inc.
Street Address
564 Lincoln Blvd.
City
Middlesex
State
NJ
ZipCode
08846
Phone Number
732-748-8606
Web Address
www.nutrabio.com
Pharmacist Counseling Corner

100% Pure L-Tryptophan 500 Milligrams by NutraBio: Common Questions

Does 100% Pure L-Tryptophan 500 Milligrams by NutraBio interact with any medications?
Yes. Based on its ingredients, 100% Pure L-Tryptophan 500 Milligrams has a known interaction with 394 medications, including 248 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
100% Pure L-Tryptophan 500 Milligrams contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What is L-Tryptophan and what's it supposed to do?
L-Tryptophan is an amino acid your body converts to serotonin, a brain chemical tied to mood and sleep. It's marketed for mood and sleep support, but the evidence for those uses is limited.
Can I take L-Tryptophan while pregnant or breastfeeding?
During pregnancy, the safety data is conflicting — some evidence suggests it may be unsafe, so it's best avoided. While breastfeeding, safety isn't established, so avoid it unless your doctor tells you otherwise. Talk to your doctor or pharmacist for personalized advice.
What side effects should I expect?
Most common are mild gastrointestinal issues like nausea, diarrhea, and heartburn, plus drowsiness, headache, and lightheadedness. These tend to be manageable. Rare serious effects linked to a contaminated batch in 1989 are not expected with modern products.
Is this safe after the 1989 contamination scare?
Almost all cases of that neurological disorder came from one Japanese manufacturer; modern L-Tryptophan products are not thought to carry that risk. But the history is why sourcing from a reputable brand like NutraBio matters.
Can I take this with my antidepressant?
Not without checking with your pharmacist first. L-Tryptophan boosts serotonin, and combining it with antidepressants could theoretically cause serotonin syndrome. Your pharmacist can tell you if your specific medication is a concern.
Will this help me sleep?
L-Tryptophan can cause drowsiness, but there isn't enough reliable evidence to say it's an effective sleep aid. If you're interested in sleep support, ask your pharmacist about what research actually backs.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

100% Pure L-Tryptophan 500 Milligrams label
Go deeper

The Full Monographs Behind 100% Pure L-Tryptophan 500 Milligrams’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

L-tryptophan

Interacts with 394 drugs

L-tryptophan is an essential amino acid the body uses to make serotonin and melatonin, and people take it to support sleep and mood. The evidence for supplement use is limited and mixed, and...

Read the full L-tryptophan monograph →
Sources

Sources & How We Checked

100% Pure L-Tryptophan 500 Milligrams's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 18 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

L-tryptophan 18 references
  1. Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. PubMed
  2. Devoe LD, Castillo RA, Searle NS. Maternal dietary substrates and human fetal biophysical activity. The effects of tryptophan and glucose on fetal breathing movements. Am J Obstet Gynecol 1986;155:135-9. DOI
  3. Lieberman HR, Corkin S, Spring BJ. The effects of dietary neurotransmitter precursors on human behavior. Am J Clin Nutr 1985;42:366-70. PubMed
  4. U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements. Information Paper on L-Tryptophan and 5-hydroxy-L-tryptophan, February 2001.
  5. Sullivan EA, Kamb ML, Jones JL, et al. The natural history of eosinophilia-myalgia syndrome in a tryptophan-exposed cohort in South Carolina. Arch Intern Med 1996;156:973-9. DOI
  6. Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. Am J Epidemiol 1993;138:154-9. PubMed
  7. Bohme A, Wolter M, Hoelzer D. L-tryptophan-related eosinophilia-myalgia syndrome possibly associated with a chronic B-lymphocytic leukemia. Ann Hematol 1998;77:235-8. PubMed
  8. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  9. Priori R, Conti F, Luan FL, et al. Chronic fatigue: a peculiar evolution of eosinophilia myalgia syndrome following treatment with L-tryptophan in four Italian adolescents. Eur J Pediatr 1994;153:344-6..
  10. Klein R, Berg PA. A comparative study on antibodies to nucleoli and 5-hydroxytryptamine in patients with fibromyalgia syndrome and tryptophan-induced eosinophilia-myalgia syndrome. Clin Investig 1994;72:541-9.. PubMed
  11. Simat TJ, Kleeberg KK, Muller B, Sierts A. Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan. Adv Exp Med Biol 1999;467:469-80.. PubMed
  12. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;(1):CD003198. PubMed
  13. Kilbourne EM, Philen RM, Kamb ML, Falk H. Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:81-8.
  14. Horwitz RI, Daniels SR. Bias or biology: evaluating the epidemiologic studies of L-tryptophan and the eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:60-72.
  15. Shapiro S. Epidemiologic studies of the association of L-tryptophan with the eosinophilia-myalgia syndrome: a critique. J Rheumatol Suppl 1996;46:44-58.
  16. Mayeno AN, Gleich GJ. The eosinophilia-myalgia syndrome: lessons from Germany. Mayo Clin Proc 1994;69:702-4. PubMed
  17. Carr L, Ruther E, Berg PA, Lehnert H. Eosinophilia-myalgia syndrome in Germany: an epidemiologic review. Mayo Clin Proc 1994;69:620-5. PubMed
  18. Ullrich SS, Fitzgerald PCE, Giesbertz P, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of intragastric administration of tryptophan on the blood glucose response to a nutrient drink and energy intake, in lean and obese men. Nutrients 2018;10(4). pii: PubMed

See these in context on the L-tryptophan monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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