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Dietary supplement

L-Lysine 500 mg Free Form Ingredients & Drug Interactions

by Vitamin World

L-Lysine 500 mg Free Form label
See full label image
Capsule Category: Amino Acid/protein
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking L-Lysine 500 mg Free Form 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: Moderate

L-Lysine 500 mg Free Form is a dietary supplement by Vitamin World with 1 active ingredient. Its ingredients are commonly taken for mental focus and alertness, coping with stress, fatigue and sleep loss.Based on those ingredients, 21 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Tyrosine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against L-Lysine 500 mg Free Form by Vitamin World

Ask about any prescription or over-the-counter medication and we check it for interactions with L-Lysine 500 mg Free Form by Vitamin World — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of L-Lysine 500 mg Free Form by Vitamin World

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 Aug 13, 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-Tyrosine, an amino acid your body uses to make several important neurotransmitters and thyroid hormones. The capsule itself also contains gelatin, silica, and vegetable magnesium stearate as inactive ingredients to hold the formula together.

Does it work?

Strong 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

This product doesn't appear to be marketed for a specific use, so we graded Tyrosine's overall clinical evidence instead.

Strong

Strong clinical evidence supports Tyrosine for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Phenylketonuria (PKU) — rated "Effective" (Natural Medicines).
  • On file: Cognitive function — rated "Possibly Effective" (Natural Medicines).
  • On file: Memory — rated "Possibly Effective" (Natural Medicines).

Tyrosine is effective for phenylketonuria (PKU), a rare genetic condition where the body can't process phenylalanine properly. For cognitive function and memory, the evidence suggests it's possibly effective — some research supports a benefit, but more data would strengthen the claim.

For athletic performance, evidence points to it being possibly ineffective. The evidence isn't established for alcohol use disorder or dementia.

The evidence, ingredient by ingredient Tyrosine

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.

Tyrosine is generally well tolerated in healthy adults, though the safety data available is limited. The most common side effects seen are fatigue, headache, heartburn, and nausea.

Larger doses (150 mg/kg) are more likely to cause headache and fatigue, and these effects can usually be improved by lowering the dose. Because long-term safety data is sparse, talk with your doctor or pharmacist before taking it regularly.

There isn't enough data on safety during pregnancy or while breastfeeding — discuss with your healthcare provider if you're in either situation to decide what's right for you.

Side effects, ingredient by ingredient Tyrosine

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Tyrosine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 21 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 doctor or pharmacist if you're on levodopa (a Parkinson's medication) — tyrosine might lower its effectiveness and you may need to space your doses apart. Also flag it if you take thyroid hormone medications, since tyrosine could boost their effects.

Use the interaction checker below to run through your exact medications.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

L-Tyrosine works best for PKU and shows promise for memory and thinking — but the evidence for other uses is weak or still being studied. If you take levodopa or thyroid medications, you'll want to check with your doctor or pharmacist first, since tyrosine can interfere with how they work.

For anyone else in good health, it's generally well tolerated, though fatigue, headache, and nausea do happen occasionally.

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 Sep 22, 2016.

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-Lysine 500 mg Free Form, straight from the product label.

Brand Vitamin World
Barcode (UPC) 074312701818
Net contents 100 Rapid Release Capsule(s)
Market status On market
Date entered into DSLD Sep 22, 2016
DSLD ID 64808
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Dairy Free, Sugar 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 L-Lysine 500 mg Free Form by Vitamin World, 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:
1 Capsule(s)
UPC/BARCODE
074312701818
IngredientAmount% DV
L-Tyrosine500 mg--

Other ingredients: Gelatin, Silica, Vegetable Magnesium Stearate

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.
FDA Statement of Identity

Amino Acid Supplement

Suggested/Recommended/Usage/Directions

Directions: For adults, take one (1) capsule four times daily, preferably on an empty stomach.

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 Statements

Amino Acids are important components of the body. L-Tyrosine is an amino acid that helps form the bioactive factors vital to cellular function and maintenance.

To reorder prod. #181 www.vitaminworld.com 1-800-228-4533

Supports cell function and maintenance

Seals/Symbols

Quality Assured

Brand IP Statement(s)

At Vitamin World we ensure the quality of all of our premium nutritional products, every step of the way. Strict quality analysis at world-class facilities guarantees that all Vitamin World products are at the highest standard of potency and purity.

2016 Vitamin World, Inc.

Nutrition from the source

Formulation

No Artificial Color, Flavor or Sweetener, No Preservatives, No Sugar, No Starch, No Milk, No Lactose, No Soy, No Gluten, No Wheat, No Yeast, No Fish. Sodium free.

Precautions

Warning: If you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use.

Discontinue use and consult your doctor if any adverse reactions occur.

Keep out of reach of children.

Do not use if seal under cap is broken or missing.

Storage

Store at room temperature.

General

Product No. 181 B181 09F

Formula

Amino Acids

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

See for yourself

L-Lysine 500 mg Free Form by Vitamin World label

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

L-Lysine 500 mg Free Form 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 L-Lysine 500 mg Free Form by Vitamin World

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

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

L-Tyrosine

Interacts with
21 drugs
500 mg per serving

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performan...

L-Tyrosine monograph & interactions

Other (inactive) ingredients: Gelatin, Silica, Vegetable Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

L-Lysine 500 mg Free Form by Vitamin World Drug Interactions

Want to check YOUR meds against L-Lysine 500 mg Free Form?

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
21Drugs
21 Moderate

Ingredients driving the most interactions

L-Tyrosine 21

Individual Drug Interactions

The ingredients in L-Lysine 500 mg Free Form interact with 21 drugs. Click any drug to see the details.

1 of the 1 ingredient in L-Lysine 500 mg Free Form interact with drugs. Each result below shows which ingredient is responsible. L-Tyrosine

Each ingredient & the kinds of drugs it affects

For each ingredient in L-Lysine 500 mg Free Form 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-Tyrosine2 drug types · 21 drugs

Levodopa

Theoretically, tyrosine might decrease the effectiveness of levodopa.
Tyrosine and levodopa compete for absorption in the proximal duodenum by the large neutral amino acid (LNAA) transport system. Advise patients to separate doses of tyrosine and levodopa by at least 2 hours.

Likelihood Probable Evidence D
Thyroid Hormone

Theoretically, tyrosine might have additive effects with thyroid hormone medications.
Tyrosine is a precursor to thyroxine and might increase levels of thyroid hormones.

Likelihood Probable Evidence D
L-Tyrosine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for L-Lysine 500 mg Free Form, from the product label.

Vitamin World

See all Vitamin World products
Name
Vitamin World, Inc.
City
Holbrook
State
NY
ZipCode
11741
Phone Number
1-800-228-4533
Web Address
www.vitaminworld.com
Pharmacist Counseling Corner

L-Lysine 500 mg Free Form by Vitamin World: Common Questions

Does L-Lysine 500 mg Free Form by Vitamin World interact with any medications?
Yes. Based on its ingredients, L-Lysine 500 mg Free Form has a known interaction with 21 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
L-Lysine 500 mg Free Form 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.
Does L-Tyrosine actually improve memory and focus?
The evidence suggests it's possibly effective for both memory and cognitive function, meaning some research supports it but we'd like to see more data. It's effective for PKU, a genetic condition, but for other memory or focus issues, the proof isn't as strong.
What are the most common side effects?
Fatigue, headache, heartburn, and nausea are the ones we see most often. Higher doses tend to cause more side effects, but lowering the dose usually helps.
Can I take this while pregnant or breastfeeding?
There isn't enough safety data to know for sure either way. Talk with your doctor or pharmacist — they can weigh the pros and cons for your specific situation.
Is this the same as L-Lysine?
No — this product is L-Tyrosine, not L-Lysine. They're both amino acids, but they do different things in your body. Make sure you're getting the one you intended.
Can I take this with my thyroid medication?
Tyrosine is a building block for thyroid hormones, so it might add to the effects of your medication. Check with your doctor or pharmacist before combining them.
Does this have any fillers or artificial ingredients?
The active ingredient is L-Tyrosine. The capsule contains gelatin, silica, and vegetable magnesium stearate as inactive ingredients to form and stabilize the capsule.

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

Not sure if L-Lysine 500 mg Free Form 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-Lysine 500 mg Free Form label
Go deeper

The Full Monographs Behind L-Lysine 500 mg Free Form’s Ingredients

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

Herb & supplement monograph

Tyrosine

Interacts with 21 drugs

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performance during short-term stress, sleep loss,...

Read the full Tyrosine monograph →
Sources

Sources & How We Checked

L-Lysine 500 mg Free Form'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 4 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.

Tyrosine 4 references
  1. Meyer JS, Welch KM, Deshmukh VD, et al. Neurotransmitter precursor amino acids in the treatment of multi-infarct dementia and Alzheimer's disease. J Amer Geriat Soc 1977;25:289-98.
  2. DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
  3. Wood DR, Reimherr FW, Wender PH. Amino acid precursors for the treatment of attention deficit disorder, residual type. Psychopharmacol Bull 1985;21:146-9.
  4. van Spronsen FJ, van Rijn M, Bekhof J. Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets. Am J Clin Nutr 2001;73:153-7. PubMed

See these in context on the Tyrosine 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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