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 Nature's Craft 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 by Nature's Craft
Ask about any prescription or over-the-counter medication and we check it for interactions with L-Lysine by Nature's Craft — 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 Nature's Craft
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
Nature's Craft L-Lysine is a single-ingredient supplement containing 1 gram (or the dose on your label) of L-lysine, an amino acid your body uses to build protein and support immune and skin health. The tablet also contains several inactive ingredients — microcrystalline cellulose, magnesium stearate, dicalcium phosphate, stearic acid, purified water, hydroxypropyl methylcellulose, glycerin, croscarmellose sodium, and silicon dioxide — which are binders, fillers, and capsule materials.
Does it work?
Moderate evidence
L-lysine is possibly effective for cold sores (herpes labialis). Research supports its use as either prevention or treatment, though more robust trials would help confirm how much and for how long to take it.
For child growth, pressure ulcers, and diabetic foot ulcers, the evidence is too sparse or weak to say whether it works — we simply don't have enough reliable data.
How safe is it?
Well-documented data
L-lysine from food is safe. As a supplement, it's generally well tolerated at typical doses, but high amounts may cause stomach upset — including abdominal pain, diarrhea, and indigestion.
Long-term safety at high doses isn't well studied. There's one case report of very high-dose lysine linked to kidney inflammation that progressed to chronic kidney failure, though this is extremely rare.
Data on lysine supplements during pregnancy and breastfeeding is not well studied, so talk with your doctor or pharmacist before taking it if you're pregnant or nursing. Food sources of lysine (chicken, beef, fish, dairy, eggs, legumes) are fine.
Meds to double-check
Minor interactions only
If you take a 5-HT4 agonist (such as cisapride or prucalopride), confirm with your doctor or pharmacist before adding L-lysine — it may reduce how well these drugs work.
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 may help prevent or shorten cold sores. It's generally well tolerated, though high doses can cause stomach upset.
If you take a 5-HT4 agonist, check with your doctor or pharmacist first. Pregnant or breastfeeding?
Talk it over with your healthcare provider 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 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, straight from the product label.
| Brand | Nature's Craft |
|---|---|
| Net contents | 100 Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Aug 23, 2023 |
| DSLD ID | 296784 |
| Product type | Amino Acid/protein |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | Nutrient, All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years) |
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 Nature's Craft, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| L-Lysine | 1000 mg | -- |
Other ingredients: Microcrystalline Cellulose, Magnesium Stearate, Dicalcium Phosphate, Stearic Acid, Water, Purified, Hydroxypropyl Methylcellulose, Glycerin, Croscarmellose Sodium, Silicon Dioxide
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.
Suggested/Recommended/Usage/Directions
Suggested Use: 2 tablets taken daily between meals or as directed by a healthcare professional.
Precautions
Caution: Do not exceed recommended dose.
Pregnant or nursing mothers, children under 18, and individuals with a known medical condition should consult a physician before using this or any dietary supplement.
Pregnant or nursing mothers, children under 18, and individuals with a known medical condition should consult a physician before using this or any dietary supplement.
This product is manufactured and packaged in a facility which may also process milk, soy, wheat, egg, peanuts, tree nuts, fish and crustacean shellfish.
Keep out of reach of children.
Do not use if safety seal is damaged or missing.
Storage
Store in a cool, dry place.
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
New Look Same Craft
Please Recycle Follow us on: twitter facebook instagram shopnaturescraft
Formulation
Supports Immune System Immune Support
FDA Statement of Identity
Dietary Supplement
Seals/Symbols
Formulated in the USA Good Manufacturing Practice GMP
Formula
Essential amino acid
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
L-Lysine by Nature's Craft 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 Nature's Craft
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size2 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: Microcrystalline Cellulose, Magnesium Stearate, Dicalcium Phosphate, Stearic Acid, Water, Purified, Hydroxypropyl Methylcellulose, Glycerin, Croscarmellose Sodium, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.
L-Lysine by Nature's Craft Drug Interactions
HelloPharmacist Interaction Report
Nature's Craft L-Lysine has one documented interaction: through its lysine 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 partly blocks these drugs' action, which could make them less effective at controlling symptoms. This is rated Minor severity.
Read the full breakdown — every affected drug type, severity by severity
If you take a 5-HT4 agonist — such as cisapride or prucalopride — for gastroparesis or irritable bowel syndrome, check with your doctor or pharmacist before starting lysine. They can decide whether you need to adjust timing or dosing, or switch approaches entirely.
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
TegaserodZelnorm
How Tegaserod interacts with L-Lysine — 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 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, from the product label.
Nature's Craft
See all Nature's Craft products- Name
- Nature's Craft
- City
- Pomona
- State
- NY
- ZipCode
- 10970
- Phone Number
- 408-599-3841
- Web Address
- shopnaturescraft.com
L-Lysine by Nature's Craft: Common Questions
Does L-Lysine by Nature's Craft 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 side effects should I expect?
Is it safe to take if I'm pregnant or nursing?
Can I take this with my other medications?
How much L-lysine should I take for cold sores?
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