L-Lysine Ingredients & Drug Interactions
What is this page for?
First and foremost: checking L-Lysine 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 is a dietary supplement by Pure Encapsulations 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 Hydrochloride. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Lysine by Pure Encapsulations
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Lysine by Pure Encapsulations — 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
Ask the Pharmacist
A licensed pharmacist will answer your question by email — free, usually within 24 hours.
Got it — thank you!
A licensed pharmacist will answer within 24 hours. Keep an eye on your email (worth checking spam, just in case).
HelloPharmacist Scorecard of L-Lysine by Pure Encapsulations
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 hydrochloride, an amino acid (a building block of protein). The capsule also contains three inactive ingredients—cellulose, water, and ascorbyl palmitate—that serve as binding and preserving agents.
Does it work?
Moderate evidence
L-lysine is possibly effective for herpes labialis, also known as cold sores. The evidence supporting its use for child growth, pressure ulcers, or diabetic foot ulcers is not yet established in the data we hold.
How safe is it?
Well-documented data
L-lysine is generally well tolerated at typical doses. Higher amounts may cause stomach upset—including abdominal pain, diarrhea, and indigestion—and long-term safety at large doses hasn't been thoroughly studied.
There is one case report of oral lysine linked to kidney inflammation progressing to chronic kidney damage, though this is rare. Supplement safety in pregnancy is not well studied, so check with your doctor first if you're pregnant or planning to become pregnant.
There isn't enough reliable information on lysine supplements during breastfeeding, so caution is advised—talk it over with your doctor or pharmacist.
Meds to double-check
Minor interactions only
5-HT4 agonists (gastrointestinal medications) may have reduced effectiveness with lysine. Check with your doctor or pharmacist before combining them.
The bottom line
Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Only minor medication interactions are documented, and safety information is well characterized.
L-lysine is possibly effective for cold sores and is generally well tolerated at normal doses. If you take a 5-HT4 agonist (a gastrointestinal medication), check with your doctor or pharmacist before starting it.
Pregnant or breastfeeding? Same thing—get personalized advice from your own 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 Jul 18, 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, straight from the product label.
| Brand | Pure Encapsulations |
|---|---|
| Barcode (UPC) | 766298012421 |
| Net contents | 270 Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Jul 18, 2023 |
| DSLD ID | 295521 |
| 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 |
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 by Pure Encapsulations, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Lysine Hydrochloride | 500 mg | -- |
Other ingredients: Cellulose, Water, Ascorbyl Palmitate
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.
Storage
Store in a cool, dry place.
Suggested/Recommended/Usage/Directions
Recommendations: As a dietary supplement, take 1 capsule, 2 times daily, between meals, or as directed by a health professional.
Precautions
Warning: If you are pregnant or lactating, have any health condition or are taking any medication, consult your health professional before use.
Keep out of reach of children.
Use only if safety seal is intact.
General Statements
Contents may not fill package in order to accommodate required labeling. Please rely on stated quantity. Scan to learn about our hypoallergenic supplements
Seals/Symbols
GFCO.org (Gluten-Free Certification Organization)
Formulation
Certified gluten free by the Gluten-Free Certification Organization, www.gluten.org
Supports immune function
Gluten-free, non-GMO & hypoallergenic
Gluten-free, non-GMO & hypoallergenic
FDA Statement of Identity
Dietary Supplement
FDA Disclaimer Statement
This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Lysine by Pure Encapsulations 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 by Pure Encapsulations
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Capsule(s) Dosage formCapsule Servings per container270 Amounts shown are per serving.
L-Lysine Hydrochloride
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 Hydrochloride monograph & interactionsOther (inactive) ingredients: Cellulose, Water, Ascorbyl Palmitate. These complete the product’s ingredient list but are not active constituents.
L-Lysine by Pure Encapsulations Drug Interactions
HelloPharmacist Interaction Report
L-Lysine by Pure Encapsulations has one documented interaction: it may reduce the effects of 5-HT4 agonists (a drug class used to treat certain gastrointestinal conditions).
Animal research suggests lysine acts as a partial blocker of the serotonin receptor that these drugs target, which could theoretically lower how well they work.
Read the full breakdown — every affected drug type, severity by severity
This is rated Minor severity. If you take a 5-HT4 agonist, talk with your doctor or pharmacist before starting lysine to see if the timing or dose of your current medication needs adjustment.
Otherwise, check your exact medications with the search tool on this page to be sure.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Lysine?
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 interact with 1 drug. Click any drug to see the details.
1 of the 1 ingredient in L-Lysine interact with drugs. Each result below shows which ingredient is responsible. L-Lysine Hydrochloride
TegaserodZelnorm
How Tegaserod interacts with L-Lysine — through 1 ingredient. Tap an ingredient for the detail:
L-lysine Hydrochloride5-ht4 Agonists Minor
Interaction Summary
Theoretically, lysine may reduce the effects of 5-HT4 agonists.
Read the full L-lysine Hydrochloride + Tegaserod interactionEach ingredient & the kinds of drugs it affects
For each ingredient in L-Lysine 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 Hydrochloride
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, from the product label.
Pure Encapsulations
See all Pure Encapsulations products- Name
- Pure Encapsulations
- Street Address
- 490 Boston Post Road
- City
- Sudbury
- State
- MA
- Phone Number
- 1-800-753-2277
- Web Address
- www.PureEncapsulations.com
L-Lysine by Pure Encapsulations: Common Questions
Does L-Lysine by Pure Encapsulations interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Does L-lysine actually help with cold sores?
What are the common side effects?
Is it safe to take L-lysine while pregnant?
What about breastfeeding?
Can I take this with other supplements or medications?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Lysine 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’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'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