L-Lysine Powder Ingredients & Drug Interactions
by Source Naturals
What is this page for?
First and foremost: checking L-Lysine Powder 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 Powder 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 Hydrochloride. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against L-Lysine Powder by Source Naturals
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Lysine Powder 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 Powder 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 a single active ingredient: L-lysine hydrochloride, an amino acid (a building block of protein). There are no inactive ingredients listed.
Does it work?
Moderate evidence
L-lysine is possibly effective for herpes labialis (cold sores) — that's what the research supports. For other uses listed — child growth, pressure ulcers, and diabetic foot ulcers — the evidence isn't solid enough for us to rate it, so we don't know if it works for those.
How safe is it?
Well-documented data
Lysine taken by mouth is generally well tolerated at typical doses. High amounts may cause stomach upset, abdominal pain, diarrhea, or indigestion, and long-term safety hasn't been well studied.
There is one case report of very high doses linked to kidney inflammation, though this is rare. If you are pregnant or breastfeeding, supplement safety isn't well studied.
Lysine from food is fine, but talk with your doctor or pharmacist before taking a supplement dose — there isn't enough data to know either way.
Meds to double-check
Minor interactions only
If you take a 5-HT4 agonist — a medication for certain gut-related conditions — clear it with your pharmacist or doctor first; lysine may reduce how well it works.
The bottom line
Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Only minor medication interactions are documented, and safety information is well characterized.
L-lysine is possibly effective for cold sores if you're looking for supplement support. It's generally well tolerated at typical doses, though high amounts can cause stomach upset.
If you take a 5-HT4 agonist or are pregnant or breastfeeding, check with your own doctor or pharmacist before starting.
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 25, 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 Powder, straight from the product label.
| Brand | Source Naturals |
|---|---|
| Barcode (UPC) | 021078001355 |
| Net contents | 3.53 Ounce(s); 100 Gram(s) |
| Market status | On market |
| Date entered into DSLD | Sep 25, 2023 |
| DSLD ID | 295947 |
| Product type | Amino Acid/protein |
| Supplement form | Powder |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Vegetarian, Adult (18 - 50 Years), Gluten Free, Dairy 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 Powder by Source Naturals, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Lysine Hydrochloride | 1.36 Gram(s) | -- |
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
Amino Acid Supplement
Formulation
Free-from powder
Suitable for vegetarians.
Contains no yeast, dairy, egg, gluten, corn, soy or wheat. Contains starch, salt, preservatives, or artificial color, flavor or fragrance.
Formula
L-Lysine is an essential amino acid which acts as a precursor for several other amino acids, including L-citrulline (needed in the body for normal protein metabolism) and L-carnitine (needed for fat metabolism). L-Lysine is crucial for 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: 1/4 to 1/2 teaspoon daily between meals.
Precautions
Note: If you are pregnant, may become pregnant, or breastfeeding, consult your health care professional before using this product.
Do not use if either tamper-evident seal is broken or missing.
Keep out of the reach of children.
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 Powder 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 Powder by Source Naturals
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size0.25 Teaspoon(s) Dosage formPowder Servings per container73 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 & interactionsL-Lysine Powder by Source Naturals Drug Interactions
HelloPharmacist Interaction Report
L-Lysine Powder by Source Naturals has one documented interaction through its L-lysine hydrochloride content: it may reduce the effects of 5-HT4 agonists (a class of drugs that work on serotonin receptors in the gut).
Animal research suggests lysine acts as a partial blocker of these receptors, which could weaken how the medication works.
Read the full breakdown — every affected drug type, severity by severity
Although this is the only interaction we have on file, it's rated Minor. If you take a 5-HT4 agonist — which includes medications for certain gastrointestinal conditions — run it through the checker below to confirm before you start this supplement.
Althogether, these interactions span 1 individual medication. We could not check interactions for every possible medication you might take, so use the search tool on this page to look up your exact prescriptions.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against L-Lysine Powder?
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 Powder interact with 1 drug. Click any drug to see the details.
1 of the 1 ingredient in L-Lysine Powder interact with drugs. Each result below shows which ingredient is responsible. L-Lysine Hydrochloride
TegaserodZelnorm
How Tegaserod interacts with L-Lysine Powder — 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 Powder 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 Powder, 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 Powder by Source Naturals: Common Questions
Does L-Lysine Powder 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 with cold sores?
What are the side effects?
Is it safe to take while pregnant?
Is it safe while breastfeeding?
How much lysine is in one serving?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if L-Lysine Powder 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 Powder’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 Powder'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