L-Lysine 500 mg Ingredients & Drug Interactions
by Source Naturals
What is this page for?
First and foremost: checking L-Lysine 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
L-Lysine 500 mg is a dietary supplement by Source Naturals with 1 active ingredient. Its ingredients are commonly taken for cold sores (herpes labialis), genital herpes outbreaks, supporting protein and collagen formation.Based on those ingredients, 1 medication has a known interaction with it, the most serious rated minor. The ingredients most likely to interact are L-Lysine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Lysine 500 mg by Source Naturals
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Lysine 500 mg by Source Naturals — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of L-Lysine 500 mg by Source Naturals
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.
What’s inside
Full disclosure
This product contains one active ingredient: L-lysine, an amino acid your body uses for protein synthesis and immune function. L-lysine is also available from foods like meat, cheese, and eggs.
The tablet includes inactive ingredients (sorbitol, stearic acid, modified cellulose gum, and magnesium stearate) that help form and stabilize the pill.
Does it work?
Not established
L-lysine is possibly effective for herpes labialis, commonly called cold sores. The evidence supports its use for this purpose.
For other potential uses—child growth, pressure ulcers, and diabetic foot ulcers—there isn't enough reliable evidence in our data to say whether it works.
How safe is it?
Well-documented data
L-lysine is generally well tolerated at typical doses, though high amounts may cause stomach upset and long-term safety hasn't been extensively studied. The most common side effects from oral use are abdominal pain, diarrhea, and indigestion.
There is one case report of lysine linked to kidney inflammation that progressed to chronic kidney failure, though this is rare. Lysine from food is fine, but supplement safety during pregnancy and breastfeeding hasn't been well studied—talk with your doctor or pharmacist before taking it if you're pregnant or nursing.
Meds to double-check
Minor interactions only
Before you take this, check with your doctor or pharmacist if you take any 5-HT4 agonists—L-lysine may reduce how well they work. No other interactions are documented for the ingredients we could check.
The bottom line
Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Only minor medication interactions are documented, and safety information is well characterized.
L-lysine is a straightforward single-ingredient supplement possibly effective for cold sores. If you're pregnant, breastfeeding, or take any medications—especially 5-HT4 agonists—check with your doctor or pharmacist before starting.
It's generally well tolerated, but high doses or long-term use may need discussion with your healthcare 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 Aug 23, 2023.
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
General information
Key facts about L-Lysine 500 mg, straight from the product label.
| Brand | Source Naturals |
|---|---|
| Barcode (UPC) | 021078001386 |
| Net contents | 50 Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Aug 23, 2023 |
| DSLD ID | 295945 |
| Product type | Amino Acid/protein |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Vegetarian, Adult (18 - 50 Years), Gluten Free, Dairy Free, Sugar Free |
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 by Source Naturals, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Lysine | 500 mg | -- |
Other ingredients: Sorbitol, Stearic Acid, Modified Cellulose Gum, Magnesium Stearate
Tap any ingredient to jump to its full detail below.
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
Dietary Supplement
Formulation
Free-Form
Suitable for vegetarians.
Contains no yeast, dairy, egg, gluten, soy or wheat. Contains no sugar, starch, salt, preservatives, or artificial color, flavor or fragrance.
Formula
L-lysine is an essential free form amino acid, which acts as a precursor for other amino acids, including L-carnitine (needed for fat metabolism). L-lysine is crucial to the formation of collagen, a major part of the body's connective tissues. L-lysine also contributes to energy production when converted to acetyl coenzyme A, one of the principal fuels for the Krebs cycle.
Suggested/Recommended/Usage/Directions
Suggested use: 1 to 2 tablets daily.
Precautions
Do not use if either tamper-evident seal is broken or missing.
Keep out of the reach of children.
Note: if you are pregnant, may become pregnant, or breastfeeding, consult your health care professional before using this product.
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)
Copyright Source Naturals, Inc.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Lysine 500 mg by Source Naturals label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in L-Lysine 500 mg by Source Naturals
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container50 Amounts shown are per serving.
L-Lysine
Interacts with1 drug
Lysine is an essential amino acid your body cannot make on its own, so it must come from food or supplements. People most often take extra lysine to t...
L-Lysine monograph & interactionsOther (inactive) ingredients: Sorbitol, Stearic Acid, Modified Cellulose Gum, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.
L-Lysine 500 mg by Source Naturals Drug Interactions
HelloPharmacist Interaction Report
Source Naturals L-Lysine 500 mg interacts with one medication type through its L-lysine content.
The documented interaction is Minor in severity: lysine may theoretically reduce the effects of 5-HT4 agonists (medications that work on serotonin receptor 4). Animal research suggests L-lysine acts as a partial antagonist to these receptors and can inhibit diarrhea caused by 5-HT4 agonists, which means it could potentially blunt how these drugs work.
Read the full breakdown — every affected drug type, severity by severity
Although this is the only interaction documented in our data for this product, it's worth checking your exact medications with the search tool on this page before you start, especially if you take any 5-HT4 agonist.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Lysine 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 checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in L-Lysine 500 mg interact with 1 drug. Click any drug to see the details.
1 of the 1 ingredient in L-Lysine 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Lysine
TegaserodZelnorm
How Tegaserod interacts with L-Lysine 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-lysine5-ht4 Agonists Minor
Interaction Summary
Theoretically, lysine may reduce the effects of 5-HT4 agonists.
Read the full L-lysine + Tegaserod interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Lysine 500 mg 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-Lysine
5-Ht4 Agonists
Theoretically, lysine may reduce the effects of 5-HT4 agonists.
Animal research suggests that L-lysine is a partial serotonin receptor 4 (5-HT4) antagonist and inhibits diarrhea induced by the 5-HT4 agonist, 5-hydroxytryptophane.
Brand information
Manufacturer and brand details for L-Lysine 500 mg, from the product label.
Source Naturals
- Name
- Source Naturals, Inc.
- Street Address
- P. O. Box 2118
- City
- Santa Cruz
- State
- CA
- ZipCode
- 95062
- Web Address
- www.sourcenaturals.com
L-Lysine 500 mg by Source Naturals: Common Questions
Does L-Lysine 500 mg by Source Naturals interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Will L-lysine help my cold sores?
What are the most common side effects?
Is it safe to take L-lysine while pregnant?
Can I take this while breastfeeding?
What is L-lysine?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Lysine 500 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
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.
The Full Monographs Behind L-Lysine 500 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
L-Lysine 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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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 7 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.
Lysine 7 references
- Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol 1984;58:659-66. PubMed
- McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis 1984;34:366-73.
- DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol 1984;120:48-51. DOI
- Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol 1980;60:85-7.
- Griffith RS, Walsh DE, Myrmel KH, et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica 1987;175:183-90. DOI
- Lo JC, Chertow GM, Rennke H, Seifter JL. Fanconi's syndrome and tubulointerstitial nephritis in association with L-lysine ingestion. Am J Kidney Dis 1996;28:614-7. PubMed
- Smriga M, Torii K. L-Lysine acts like a partial serotonin receptor 4 antagonist and inhibits serotonin-mediated intestinal pathologies and anxiety in rats. Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15370-5.
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