Natural L-Lysine HCl 500 mg Ingredients & Drug Interactions
What is this page for?
First and foremost: checking Natural L-Lysine HCl 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
Natural L-Lysine HCl 500 mg is a dietary supplement by Quality Choice 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 Monohydrochloride. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against Natural L-Lysine HCl 500 mg by Quality Choice
Ask about any prescription or over-the-counter medication and we check it for interactions with Natural L-Lysine HCl 500 mg by Quality Choice — 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 Natural L-Lysine HCl 500 mg by Quality Choice
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 monohydrochloride, an amino acid that your body uses for protein building and immune support. Each tablet delivers 500 mg.
The inactive ingredients are water, powdered cellulose, soy polysaccharides, stearic acid, colloidal silicon dioxide, and magnesium stearate—these are the excipients that hold the tablet together and keep it stable on the shelf.
Does it work?
Insufficient evidence
L-lysine is possibly effective for herpes labialis (cold sores). The evidence supporting other uses—child growth, pressure ulcers, and diabetic foot ulcers—is not strong enough to rate yet.
If you're taking lysine specifically for cold sores, there's reasonable support for that; for other reasons, the data we hold doesn't establish clear benefit.
How safe is it?
Well-documented data
L-lysine is generally well tolerated at normal doses. The most common side effects are stomach upset—abdominal pain, diarrhea, and indigestion—especially if you take high amounts.
Long-term safety at very high doses hasn't been thoroughly studied. For pregnancy, there isn't enough reliable data on supplement use to say it's safe or unsafe, so talk with your doctor before taking it while pregnant.
The same goes for breastfeeding—we don't have enough information, so caution is advised and you should check with your doctor or pharmacist first.
Meds to double-check
Minor interactions only
If you take a 5-HT4 agonist (a drug that works on serotonin receptor 4 in your gut), double-check with your doctor or pharmacist before adding L-lysine, since lysine may reduce how well the drug works. For all other medications we could check, no interactions are documented.
The bottom line
Scorecard at a glanceFully disclosed formula with insufficient evidence for its stated purpose. Only minor medication interactions are documented, and safety information is well characterized.
Quality Choice's L-Lysine is a straightforward one-ingredient supplement possibly effective for cold sores. It's generally well tolerated, though high doses may cause stomach upset.
If you take a 5-HT4 agonist or are pregnant or breastfeeding, check with your doctor or pharmacist before starting it.
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 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
General information
Key facts about Natural L-Lysine HCl 500 mg, straight from the product label.
| Brand | Quality Choice |
|---|---|
| Barcode (UPC) | 635515903340 |
| Net contents | 100 Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Oct 25, 2013 |
| DSLD ID | 26088 |
| Product type | Amino Acid/protein |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | All Other |
| Intended target group(s) | Adult (18 - 50 Years), Gluten 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 Natural L-Lysine HCl 500 mg by Quality Choice, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Lysine Monohydrochloride | 500 mg | -- |
Other ingredients: Water, powdered Cellulose, Soy Polysaccharides, Stearic Acid, Silicon Dioxide, Colloidal, 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.
Seals/Symbols
SATISFACTION GUARANTEED QC
QC QUALITY CHOICE(R)
BUY WITH CONFIDENCE
General
129810 QC642463 786-EOEK
General Statements
Essential For Growth & Development
L-Lysine Monohydrocholoride is an integral part of the Amino Acid spectrum.
L-Lysine is an Amino Acid that functions as a building block of proteins.
MADE IN USA
FDA Statement of Identity
Dietary Supplement
Brand IP Statement(s)
(C) DISTRIBUTED BY QUALITY CHOICE
Formulation
NO ARTIFICIAL COLORS OR FLAVORS - NO SALT - NO YEAST NO CHEMICAL SOLVENTS - NO SUGAR - NO WHEAT NO PRESERVATIVES - NO STARCH - NO LACTOSE NO GLUTEN - NO TRANS FAT
Precautions
SAFETY SEALED. DO NOT USE IF PRINTED SEAL UNDER CAP IS CUT, TORN OR MISSING.
Keep out of the reach of children.
Suggested/Recommended/Usage/Directions
Directions: Adults - One tablet daily as a dietary supplement.
Storage
Store in a dry place 15(0)-30(0) C (59(0)-86(0)F).
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
Natural L-Lysine HCl 500 mg by Quality Choice 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 Natural L-Lysine HCl 500 mg by Quality Choice
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 Amounts shown are per serving.
L-Lysine Monohydrochloride
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 Monohydrochloride monograph & interactionsOther (inactive) ingredients: Water, Powdered Cellulose, Soy Polysaccharides, Stearic Acid, Silicon Dioxide, Colloidal, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.
Natural L-Lysine HCl 500 mg by Quality Choice Drug Interactions
HelloPharmacist Interaction Report
Quality Choice's Natural L-Lysine HCl 500 mg contains one active ingredient—L-lysine—which has a documented interaction with 5-HT4 agonists (drugs that work on a specific serotonin receptor in your gut).
The concern is Minor in severity: lysine may reduce how well these medications work.
Read the full breakdown — every affected drug type, severity by severity
This interaction is based on animal research showing that L-lysine partly blocks the serotonin receptor 4 (5-HT4) that these drugs activate. In practice, it's a small risk, but if you take a 5-HT4 agonist for stomach or bowel issues, it's worth a quick conversation with your doctor or pharmacist before adding this supplement.
Altogether, these interactions span 1 individual medication. Use the medication checker on this page to see if your exact drugs are affected, and confirm with your own healthcare provider before combining them with lysine.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against Natural L-Lysine HCl 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 Natural L-Lysine HCl 500 mg interact with 1 drug. Click any drug to see the details.
1 of the 1 ingredient in Natural L-Lysine HCl 500 mg interact with drugs. Each result below shows which ingredient is responsible. L-Lysine Monohydrochloride
TegaserodZelnorm
How Tegaserod interacts with Natural L-Lysine HCl 500 mg — through 1 ingredient. Tap an ingredient for the detail:
L-lysine Monohydrochloride5-ht4 Agonists Minor
Interaction Summary
Theoretically, lysine may reduce the effects of 5-HT4 agonists.
Read the full L-lysine Monohydrochloride + Tegaserod interactionEach ingredient & the kinds of drugs it affects
For each ingredient in Natural L-Lysine HCl 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 Monohydrochloride
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 Natural L-Lysine HCl 500 mg, from the product label.
Quality Choice
See all Quality Choice products- Name
- QUALITY CHOICE
- City
- NOVI
- State
- MI
- ZipCode
- 48376-0995
Natural L-Lysine HCl 500 mg by Quality Choice: Common Questions
Does Natural L-Lysine HCl 500 mg by Quality Choice interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Does L-lysine really help with cold sores?
What side effects should I watch for?
Can I take this while pregnant?
Is L-lysine safe while breastfeeding?
How much L-lysine is in each tablet?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if Natural L-Lysine HCl 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 Natural L-Lysine HCl 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
Natural L-Lysine HCl 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