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Dietary supplement

L-Tryptophan Ingredients & Drug Interactions

by Vitamin Research Products

Capsule Category: Amino Acid/protein
Most serious interaction: Major
The interaction bottom line Most serious interaction: Major

L-Tryptophan is a dietary supplement by Vitamin Research Products 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.

HelloPharmacist Scorecard of L-Tryptophan by Vitamin Research Products

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

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, an amino acid that your body uses to make serotonin, a neurotransmitter tied to mood and sleep. The capsule also holds hydroxypropylmethylcellulose, an inactive binder.

Does it work?

Not established
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 established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use — see L-tryptophan's own graded uses on its monograph.

Why this rating?
  • The label markets this product for: mood, calm, relaxation and sleep support.
  • We looked for evidence on: Anxiety, Depression, Seasonal affective disorder (SAD), Sleep apnea, Premenstrual dysphoric disorder (PMDD), Premenstrual syndrome (PMS) — and 2 related terms.
  • The closest evidence on file: L-tryptophan is rated "Possibly Ineffective" for Depression (Natural Medicines).
  • Also on file: L-tryptophan is rated "Insufficient Reliable Evidence To Rate" for Anxiety, Sleep apnea, Premenstrual dysphoric disorder (PMDD), Premenstrual syndrome (PMS), and more.

The evidence for L-tryptophan is mixed. For depression, it's rated possibly ineffective.

For anxiety, athletic performance, teeth grinding (bruxism), and premenstrual dysphoric disorder (PMDD), we don't have enough reliable evidence to say whether it works.

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, though common side effects include belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting. There is a history of contamination: in 1989, over 1,500 cases of eosinophilia-myalgia syndrome (EMS), a serious neurological disorder, were tied to L-tryptophan — but about 95% of those cases traced back to a single contaminated manufacturer in Japan, and the product was recalled and restricted by the FDA in 1990.

During pregnancy, safety data is conflicting — some evidence suggests it may be unsafe, so talk with your doctor or pharmacist about whether it's right for you. While breastfeeding, there isn't enough safety data, so it's best avoided unless you've cleared it with your healthcare provider.

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.

Before taking L-tryptophan, double-check with your doctor or pharmacist if you're on any CNS depressants (including alcohol, sedatives, and opioid painkillers) or serotonergic drugs such as antidepressants, migraine medications, or other mood-related prescriptions. These are the two main interaction risks.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Major medication interactions have been identified, and safety information is well characterized.

L-tryptophan may appeal to you if you're exploring options for mood or sleep support, but it's not a proven fix for depression and the evidence for other uses is sparse. If you take any sedatives, antidepressants, or migraine medications, you'll need to check with your own doctor or pharmacist before starting it — the interaction risks are real.

Pregnancy and breastfeeding also require a conversation with your provider.

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 Jun 25, 2014.

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 L-Tryptophan, straight from the product label.

Brand Vitamin Research Products
Barcode (UPC) 892727000124
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Jun 25, 2014
DSLD ID 34051
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 L-Tryptophan by Vitamin Research Products, 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:
2 Capsule(s)
Maximum serving Sizes:
4 Capsule(s)
Servings per container
23
UPC/BARCODE
892727000124
IngredientAmount% DV
L-Tryptophan2 Gram(s)--

Other ingredients: Hydroxypropylmethylcellulose

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

Directions: Take 2-4 capsules one hour before bedtime on an empty stomach.

General Statements

Description: The amino acid L-Tryptophan helps boost levels of serotonin, a mood-enhancing neurotransmitter involved in promoting a sense of well being, calm, personal security, relaxation, confidence, concentration and appetite control.

This product is manufactured in a NSF GMP registered facility.

Since 1979

TESTED FOR QUALITY & PURITY

Code Number: 8901

Precautions

Caution: If you are under a physician's care or are taking medication, or if you are pregnant or nursing, consult your healthcare professional before using this product.

Keep out of reach of children.

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.

Seals/Symbols

LABORATORY TESTED QUALITY & PURITY

VRP

General

300-VRP8901-F

FDA Statement of Identity

Dietary Supplement

Storage

Keep container tightly closed in a cool, dry and dark place.

See for yourself

L-Tryptophan by Vitamin Research Products label

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

What’s inside

The Ingredients in L-Tryptophan by Vitamin Research Products

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

Serving size2 Capsule(s) Dosage formCapsule Servings per container23 Amounts shown are per serving.

L-Tryptophan

Interacts with
394 drugs
2 Gram(s) 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: Hydroxypropylmethylcellulose. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Tryptophan by Vitamin Research Products Drug Interactions

Want to check YOUR meds against L-Tryptophan?

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

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Tryptophan 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
The maker

Brand information

Manufacturer and brand details for L-Tryptophan, from the product label.

Vitamin Research Products

See all Vitamin Research Products products
Name
VRP Brand, LLC
Street Address
4610 Arrowhead Dr.
City
Carson City
State
NV
ZipCode
89706
Phone Number
1-800-877-2447
Web Address
www.vrp.com
Pharmacist Counseling Corner

L-Tryptophan by Vitamin Research Products: Common Questions

Does L-Tryptophan by Vitamin Research Products interact with any medications?
Yes. Based on its ingredients, L-Tryptophan 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?
L-Tryptophan 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 does L-tryptophan actually do in my body?
L-tryptophan is an amino acid your body converts into serotonin, a chemical that influences mood, sleep, and other functions. It's one of nine essential amino acids you need from food or supplements because your body can't make it on its own.
Is L-tryptophan safe during pregnancy?
The safety data conflict — some evidence suggests it may be unsafe during pregnancy. Talk with your doctor or pharmacist about your specific situation before taking it while pregnant.
Can I take this while breastfeeding?
There isn't enough safety data to know whether L-tryptophan is safe while breastfeeding. Check with your doctor or pharmacist before using it.
I've heard L-tryptophan caused serious illness in the past — is it still safe?
In 1989, over 1,500 cases of a neurological disorder called EMS were linked to L-tryptophan, but about 95% traced to one contaminated batch from a single Japanese manufacturer. The product was recalled and restricted by the FDA in 1990. Current products aren't from that contaminated source, but be aware of this history.
Does L-tryptophan actually help with depression?
The evidence suggests it's probably not effective for depression. The data we have rates it as possibly ineffective for that use.
What side effects might I notice?
Common ones include drowsiness, nausea, headache, diarrhea, stomach upset, and dry mouth. Most people tolerate it well, but if you notice severe or unusual symptoms, talk with your pharmacist or doctor.

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

Not sure if L-Tryptophan is safe with your meds?

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Ask a pharmacist

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.

L-Tryptophan label
Sources

Sources & How We Checked

L-Tryptophan'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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