Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

Best L-Tryptophan 500 mg Ingredients & Drug Interactions

by Doctor's Best

Best L-Tryptophan 500 mg label
See full label image
Capsule Category: Botanical With Nutrients
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Best L-Tryptophan 500 mg 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

Best L-Tryptophan 500 mg is a dietary supplement by Doctor's Best with 3 active ingredients. Its ingredients are commonly taken for morning sickness in pregnancy, premenstrual syndrome (pms), preventing or treating b6 deficiency.Based on those ingredients, 1,044 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Niacin, L-Tryptophan, Vitamin B6. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Best L-Tryptophan 500 mg by Doctor's Best

Ask about any prescription or over-the-counter medication and we check it for interactions with Best L-Tryptophan 500 mg by Doctor's Best — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Best L-Tryptophan 500 mg by Doctor's Best

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 3 of its 3 active ingredients.
  • “Vitamin B6” is listed as a grouped ingredient — the label gives one combined amount (10 mg) without saying how much of each component you get.

This product contains 3 active ingredients: L-tryptophan (the main one at 500 mg per capsule), niacin, and vitamin B6 (17.6 mg as pyridoxal 5-phosphate). L-tryptophan is an amino acid your body uses to make serotonin, a chemical messenger in the brain.

Niacin is a B vitamin needed for energy and cell health. Vitamin B6 helps your body process amino acids and make neurotransmitters.

The capsules also contain inactive ingredients: modified cellulose, cellulose, magnesium stearate, and silicon dioxide—these are fillers and binders that hold the capsule together.

Does it work?

Moderate evidence
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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: Sleep and mood support.
  • We looked for evidence on: Anxiety, Depression, Insomnia, Postpartum depression, Premenstrual dysphoric disorder (PMDD), Premenstrual syndrome (PMS) — and 4 related terms.
  • The strongest evidence on file: Vitamin B6 is rated "Possibly Effective" for Premenstrual syndrome (PMS) (Natural Medicines).
  • Also on file: L-tryptophan is rated "Possibly Ineffective" for Depression.
  • Also on file: L-tryptophan is rated "Insufficient Reliable Evidence To Rate" for Anxiety, Premenstrual dysphoric disorder (PMDD), Premenstrual syndrome (PMS), Seasonal affective disorder (SAD).

The evidence for L-tryptophan in depression is weak—research rates it as possibly ineffective. For anxiety, athletic performance, teeth grinding (bruxism), and premenstrual dysphoric disorder, there isn't enough reliable evidence to say whether it works or not.

Niacin's track record is stronger: it's likely effective for pellagra (a serious B3 deficiency disease) and possibly effective for HIV/AIDS-related cholesterol problems and metabolic syndrome. Vitamin B6 is effective for treating B6 deficiency itself and sideroblastic anemia, likely effective for high homocysteine levels, and possibly effective for pregnancy-related nausea.

The evidence, ingredient by ingredient Vitamin B6 L-tryptophan Niacin

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 3 of the 3 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 3 of 3.
  • General safety write-ups exist for 3 of 3.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

L-tryptophan is generally well tolerated in normal doses, but it's caused side effects in some people—belching, diarrhea, drowsiness, dry mouth, gas, headache, heartburn, lightheadedness, nausea, stomach pain, blurred vision, and vomiting are the most common. There's also a historical safety concern: in the 1980s, a batch of contaminated L-tryptophan from one Japanese manufacturer caused over 1,500 cases of a rare neurological disorder called eosinophilia-myalgia syndrome (EMS); the product was recalled and remains under FDA limits.

The data advises against L-tryptophan in pregnancy and while breastfeeding. Niacin at food levels and standard supplement doses is safe; at high therapeutic doses it can cause flushing (up to 70% of users), liver problems, and gastrointestinal upset.

It's safe in pregnancy and lactation at normal amounts, but high-dose niacin should be avoided unless prescribed. Vitamin B6 is well tolerated below 100 mg daily; very high doses over time can cause nerve damage (sensory neuropathy).

Normal dietary and standard supplement amounts are fine; high doses without medical guidance should be avoided.

Side effects, ingredient by ingredient Vitamin B6 L-tryptophan Niacin

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?
  • 3 of the 3 matched ingredients can interact with medications — L-tryptophan, Niacin, Vitamin B6.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; diabetes medications; Parkinson's medications.
  • For scale: 1,045 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 this product, check with your pharmacist if you use CNS depressants (sedatives, sleep aids, some pain relievers) or serotonergic drugs (most antidepressants, some migraine treatments)—these carry Major or Moderate risk. Also check any blood pressure medications, diabetes drugs, statins, seizure medications, blood thinners, gout treatments, or liver-metabolized drugs, since niacin and vitamin B6 can interact with these at a Moderate level.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

This supplement is mainly for people interested in L-tryptophan's effects on mood and sleep, though the evidence is mixed. If you take any CNS depressants, antidepressants, blood pressure meds, diabetes drugs, statins, seizure meds, or blood thinners, talk with your pharmacist before adding this product.

The niacin and B6 content adds extra medication interactions you'll want to check. Anyone pregnant or breastfeeding should avoid it.

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

Assessment coverage: 3 of 3 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Sep 25, 2013.

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 Best L-Tryptophan 500 mg, straight from the product label.

Brand Doctor's Best
Barcode (UPC) 753950001619
Net contents 90 Veggie Cap(s)
Market status On market
Date entered into DSLD Sep 25, 2013
DSLD ID 25210
Product type Botanical With Nutrients
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegetarian, 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 Best L-Tryptophan 500 mg by Doctor's Best, 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 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
90
UPC/BARCODE
753950001619
IngredientAmount% DV
Vitamin B610 mg500%
L-Tryptophan500 mg--
Niacin20 mg100%
from 17.6 mg pyridoxal 5-phosphate17.6 mg--

Other ingredients: Modified Cellulose, Cellulose, Magnesium Stearate, Silicon Dioxide

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.
General

R 10/10

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.

Brand IP Statement(s)

Science-Based Nutrition(TM)

AjiPure(TM) and TryptoPure(TM) are trademarks of Ajinomoto Co. Inc.

FDA Statement of Identity

Dietary Supplement

General Statements

USP Pharmaceutical Grade

CONTAINS NOTHING OTHER THAN LISTED INGREDIENTS

L-tryptophan is an essential amino acid (protein building block) in human nutrition. Essential amino acids are not synthesized by the body and must be obtained in the diet. The L-tryptophan in this product is manufactured and tested for purity according to the Japanese Pharmacopeia (JP) and the United States Pharmacopeia (USP) standards. Vitamin B6 is an essential cofactor in the conversion of tryptophan, while niacinamide plays an important role in allowing our body to properly utilize this essential amino acid.

Formula

Featuring Ajinomoto's TryptoPure(TM)

500mg L-Tryptophan

Enhanced With Vit.B6 & Niacinamide

Suggested/Recommended/Usage/Directions

Suggested Adult Use: Take 1 or 2 capsules daily. For optimum absorption, take separately from protein-containing foods and dietary supplements containing protein or amino acids.

Formulation

Suitable for Vegetarians

Seals/Symbols

AJIPURE(TM) AMINO ACIDS

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

See for yourself

Best L-Tryptophan 500 mg by Doctor's Best label

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

Best L-Tryptophan 500 mg 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 Best L-Tryptophan 500 mg by Doctor's Best

These are the 3 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Servings per container90 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Vitamin B6

Interacts with
210 drugs
10 mg per serving

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is b...

Vitamin B6 monograph & interactions

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

Niacin

Interacts with
727 drugs
20 mg per serving Form: Niacinamide

Niacin (vitamin B3) is an essential nutrient your body needs for energy and metabolism, and deficiency is uncommon in most developed countries. Prescr...

Niacin monograph & interactions

Other (inactive) ingredients: Modified Cellulose, Cellulose, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Best L-Tryptophan 500 mg by Doctor's Best Drug Interactions

Want to check YOUR meds against Best L-Tryptophan 500 mg?

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
1,044Drugs
248 Major 791 Moderate 5 Minor

Ingredients driving the most interactions

Niacin 727
L-Tryptophan 394
Vitamin B6 210

Individual Drug Interactions

The ingredients in Best L-Tryptophan 500 mg interact with 1,044 drugs. Click any drug to see the details.

3 of the 3 ingredients in Best L-Tryptophan 500 mg interact with drugs. Each result below shows which ingredient is responsible. Niacin L-Tryptophan Vitamin B6

Each ingredient & the kinds of drugs it affects

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

Niacin15 drug types · 727 drugs

Alcohol (Ethanol)

Concomitant use of alcohol and niacin might increase the risk of flushing and hepatotoxicity.
Alcohol can exacerbate the flushing and pruritus associated with niacin. Large doses of niacin might also exacerbate liver dysfunction associated with chronic alcohol use. A case report describes delirium and lactic acidosis in a patient taking niacin 3 grams daily who ingested 1 liter of wine. Advise patients to avoid large amounts of alcohol while taking niacin.

Likelihood Probable Evidence D
Allopurinol (Zyloprim)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as allopurinol.
Large doses of niacin can reduce urinary excretion of uric acid, potentially resulting in hyperuricemia. Doses of uricosurics such as allopurinol might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Anticoagulant/Antiplatelet Drugs

Theoretically, niacin may have additive effects when used with anticoagulant or antiplatelet drugs.
Several cases of clotting factor synthesis deficiency and coagulopathy have been reported in patients taking sustained-release niacin. Also, thrombocytopenia has been reported in patients treated with niacin or niacin plus lovastatin.

Likelihood Possible Evidence D
Antidiabetes Drugs

Niacin can increase blood glucose levels and may diminish the effects of antidiabetes drugs.
Niacin impairs glucose tolerance in a dose-dependent manner, probably by causing or aggravating insulin resistance and increasing hepatic production of glucose. In diabetes patients, niacin 4.5 grams daily for 5 weeks can increase plasma glucose by an average of 16% and glycated hemoglobin (HbA1c) by 21%. However, lower doses of 1.5 grams daily or less appear to have minimal effects on blood glucose. In some patients, glucose levels increase when niacin is started, but then return to baseline when a stable dose is reached. Up to 35% of patients with diabetes may need adjustments in hypoglycemic therapy when niacin is added.

Likelihood Probable Evidence B
Antihypertensive Drugs

Theoretically, niacin may increase the risk of hypotension when used with antihypertensive drugs.
The vasodilating effects of niacin can cause hypotension. Furthermore, some clinical evidence suggests that a one-hour infusion of niacin can reduce systolic, diastolic, and mean blood pressure in hypertensive patients. This effect is not observed in normotensive patients.

Likelihood Possible Evidence B
Bile Acid Sequestrants

Bile acid sequestrants can bind niacin and decrease absorption. Separate administration by 4-6 hours to avoid an interaction.
In vitro studies show that colestipol (Colestid) binds about 98% of available niacin and cholestyramine (Questran) binds 10% to 30%.

Likelihood Possible Evidence D
Gemfibrozil (Lopid)

Theoretically, concomitant use of niacin and gemfibrozil might increase the risk of myopathy in some patients.
A case of myopathy from concomitant use of niacin and gemfibrozil has been reported. Niacin alone has also been associated with cases of myopathy. Using gemfibrozil with niacin might further increase the risk of developing myopathy.

Likelihood Possible Evidence D
Hepatotoxic Drugs

Theoretically, concomitant use of niacin and hepatotoxic drugs might increase the risk of hepatotoxicity.
Niacin has been associated with cases of liver toxicity, especially when used in pharmacologic doses. Sustained-release niacin preparations appear to be associated with a higher risk of hepatotoxicity than immediate-release niacin.

Likelihood Possible Evidence D
Hmg-Coa Reductase Inhibitors ("Statins")

Theoretically, concomitant use of niacin and statins might increase the risk of myopathy and rhabdomyolysis in some patients.
Some case reports have raised concerns that niacin might increase the risk of myopathy and rhabdomyolysis when combined with statins. However, a significantly increased risk of myopathy has not been demonstrated in clinical trials, including those using an FDA-approved combination of lovastatin and niacin (Advicor).

Likelihood Possible Evidence D
Probenecid (Benemid)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as probenecid.
Large doses of niacin reduce urinary excretion of uric acid, potentially causing hyperuricemia. Doses of uricosurics such as probenecid might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Sulfinpyrazone (Anturane)

Theoretically, niacin might antagonize the therapeutic effects of uricosurics such as sulfinpyrazone.
Large doses of niacin reduce urinary excretion of uric acid, potentially causing hyperuricemia. Doses of uricosurics such as sulfinpyrazone might need to be increased to maintain control of gout in patients who start taking niacin. People who have frequent attacks of gout despite uricosuric therapy should avoid niacin.

Likelihood Probable Evidence C
Thyroid Hormone

Theoretically, niacin might antagonize the therapeutic effects of thyroid hormones.
Clinical research and case reports suggests that taking niacin can reduce serum levels of thyroxine-binding globulin by up to 25% and moderately reduce levels of thyroxine (T4). Patients taking thyroid hormone for hypothyroidism might need dose adjustments when using niacin.

Likelihood Probable Evidence D
Transdermal Nicotine (Nicoderm)

Theoretically, concomitant use of niacin and transdermal nicotine might increase the risk of flushing and dizziness.
Niacin and nicotine can both cause flushing and dizziness.

Likelihood Possible Evidence D
Warfarin (Coumadin)

There is limited evidence that niacin may increase the anticoagulant effects of warfarin.
In a case report, a patient on warfarin developed an elevated international normalized ratio (INR) of 3.9 after taking niacin for two weeks. The patient's INR was previously stable, ranging between 2 and 3 in recent months, and no other medication changes were identified. The elevated INR returned to therapeutic range within 4 days following the discontinuation of niacin.

Likelihood Possible Evidence D
Aspirin

Large doses of aspirin might alter the clearance of niacin.
Aspirin is often used with niacin to reduce niacin-induced flushing. Doses of 80-975 mg aspirin have been used, but 325 mg appears to be optimal. Aspirin also seems to reduce the clearance of niacin by competing for glycine conjugation. Taking aspirin 1 gram seems to reduce niacin clearance by 45%. This is probably a dose-related effect and not clinically significant with the more common aspirin dose of 325 mg.

Likelihood Likely Evidence B
Niacin full monograph & interactions

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

Vitamin B65 drug types · 210 drugs

Amiodarone (Cordarone)

Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.
Despite initial case reports suggesting that pyridoxine may have a protective effect against amiodarone-induced photosensitivity, preliminary clinical research suggests that pyridoxine may actually exacerbate this adverse effect.

Likelihood Possible Evidence B
Antihypertensive Drugs

Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.
Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure. Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenobarbital, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenobarbital to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Phenytoin (Dilantin)

High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenytoin, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenytoin to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Levodopa

Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.
Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people.

Likelihood Unlikely Evidence D
Vitamin B6 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Best L-Tryptophan 500 mg, from the product label.

Doctor's Best

See all Doctor's Best products
Name
Doctor's Best, Inc.
City
San Clemente
State
CA
ZipCode
92673
Phone Number
(800) 777-2474
Web Address
www.drbvitamins.com
Pharmacist Counseling Corner

Best L-Tryptophan 500 mg by Doctor's Best: Common Questions

Does Best L-Tryptophan 500 mg by Doctor's Best interact with any medications?
Yes. Based on its ingredients, Best L-Tryptophan 500 mg has a known interaction with 1,044 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?
Best L-Tryptophan 500 mg contains 3 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is 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.
Will this make me drowsy?
L-tryptophan can cause drowsiness and fatigue in some people. If you take sedatives or sleep aids, this could be a real concern because the effects might add up. Let your pharmacist know if you're sensitive to drowsiness.
Can I take this with my antidepressant?
Not without checking first. L-tryptophan and many antidepressants both raise serotonin, and combining them theoretically risks serotonin syndrome—a serious condition with agitation, confusion, and fever. Your pharmacist needs to look at your specific medication.
Is it true L-tryptophan caused illness in the past?
Yes. In the late 1980s, a contaminated batch from one manufacturer caused over 1,500 cases of a neurological disorder called eosinophilia-myalgia syndrome. The product was recalled and the FDA now limits importation. Modern L-tryptophan is produced under tighter controls, but the history matters.
Is this safe if I'm pregnant or breastfeeding?
The safety data advises against L-tryptophan in pregnancy and while breastfeeding. Talk with your doctor or midwife about whether this product is right for you—there may be safer alternatives for what you're trying to address.
What does niacin in this product do?
Niacin is vitamin B3, needed for energy and cell health. At the dose in this supplement, its role is mainly to support B vitamin balance. At much higher therapeutic doses, niacin is used to manage cholesterol, but those carry more side effects like flushing and liver stress.
Can high doses of vitamin B6 hurt my nerves?
Yes, very high doses over time can cause sensory neuropathy—numbness and tingling, usually in the hands and feet. The amount in this product is small, but if you're also taking other B6 supplements or high-dose supplements elsewhere, your total adds up. Check with your pharmacist about your full B6 intake.

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.

Best L-Tryptophan 500 mg label
Go deeper

The Full Monographs Behind Best L-Tryptophan 500 mg’s Ingredients

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

Herb & supplement monograph

Vitamin B6

Interacts with 210 drugs

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is best known for helping with pregnancy-rel...

Read the full Vitamin B6 monograph → 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 → Herb & supplement monograph

Niacin

Interacts with 727 drugs

Niacin (vitamin B3) is an essential nutrient your body needs for energy and metabolism, and deficiency is uncommon in most developed countries. Prescription-strength niacin has been used to...

Read the full Niacin monograph →
Sources

Sources & How We Checked

Best L-Tryptophan 500 mg'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 116 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.

Vitamin B6 32 references
  1. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  2. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  3. Geerling BJ, Dagnelie PC, Badart-Smook A, et al. Diet as a risk factor for the development of ulcerative colitis. Am J Gastroenterol 2000;95:1008-13. PubMed
  4. South M. Neonatal seizures after pyridoxine use -- reply. Lancet 1999;354:2083. PubMed
  5. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  6. Baxter P, Aicardi J. Neonatal seizures after pyridoxine use. Lancet 1999;354:2082-3. PubMed
  7. Bendich A, Cohen M. Vitamin B6 safety issues. Ann N Y Acad Sci 1990;585:321-30.
  8. Schaumburg H, Kaplan J, Windebank A. Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome. N Engl J Med 1983;309:445-8. PubMed
  9. Gordon N. Pyridoxine dependency: an update. Dev Med Child Neurol 1997;39:63-5. PubMed
  10. Lewis PJ. Pain in the hand and wrist. Pyridoxine supplements may help patients with carpal tunnel syndrome. BMJ 1995;310:1534. PubMed
  11. Kaufman G. Pyridoxine against amiodarone-induced photosensitivity (letter). Lancet 1984;1:51-2. PubMed
  12. Mulrow JP, Mulrow CD, McKenna WJ. Pyridoxine and amiodarone-induced photosensitivity. Ann Intern Med 1985;103:68-9. PubMed
  13. Kawada A, Kashima A, Shiraishi H, et al. Pyridoxine-induced photosensitivity and hypophosphatasia. Dermatology 2000;201:356-60.. PubMed
  14. Vasile A, Goldberg R, Kornberg B. Pyridoxine toxicity: report of a case. J Am Osteopath Assoc 1984;83:790-1. DOI
  15. Hansson O, Sillanpaa M. Pyridoxine and serum concentration of phenytoin and phenobarbitone. Lancet 1976;1:256. DOI
  16. Jansen T, Romiti R, Kreuter A, Altmeyer P. Rosacea fulminans triggered by high-dose vitamins B6 and B12. J Eur Acad Dermatol Venereol 2001;15:484-5..
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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.

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