Interactions on record — worth a quick check against your medications. Check your meds →
Dietary supplement

Lysine 400 Ingredients & Drug Interactions

by ProCaps Laboratories

Lysine 400 label
See full label image
Capsule Category: Amino Acid/protein
Most serious interaction: Minor
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Lysine 400 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

The interaction bottom line Most serious interaction: Minor

Lysine 400 is a dietary supplement by ProCaps Laboratories 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.

Jump to a section

Check Your Meds Against Lysine 400 by ProCaps Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with Lysine 400 by ProCaps Laboratories — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of Lysine 400 by ProCaps Laboratories

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.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

Lysine 400 contains one active ingredient: L-lysine, an amino acid your body uses to build protein and fight infection. Each capsule provides 400 mg.

The capsule itself is made from gelatin, an inactive ingredient that holds the lysine inside.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: immune supportive amino acid.
  • We looked for evidence on: Herpes labialis (cold sores), Genital herpes, Herpes simplex, Viral immunity.
  • The strongest evidence on file: Lysine is rated "Possibly Effective" for Herpes labialis (cold sores) (Natural Medicines).

The evidence supports lysine as possibly effective for cold sores (herpes labialis). For other uses—child growth, pressure ulcers, and diabetic foot ulcers—we don't have enough reliable data to rate whether it works.

The evidence, ingredient by ingredient Lysine

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Lysine is generally well tolerated at typical doses. The most common side effects from oral use are abdominal pain, diarrhea, and indigestion.

High amounts may cause stomach upset, and long-term safety hasn't been thoroughly studied. Because supplement safety in pregnancy isn't well studied, check with your doctor before using lysine while pregnant.

There isn't enough data on breastfeeding either, so talk to your doctor or pharmacist first if you're nursing.

Side effects, ingredient by ingredient Lysine

Meds to double-check

Minor interactions only
Known Interaction Concern · database check
Minor only

Only Minor-severity interactions are documented for these ingredients.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Lysine.
  • The most serious interaction on file is rated Minor.
  • For scale: 1 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

If you take a 5-HT4 agonist (a gut motility medication), check with your pharmacist before starting lysine—it may reduce how well the drug works. No other interactions are documented for the ingredient we checked.

Check your own medication Run your meds through the checker above

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.

This is a single-ingredient supplement mainly used for cold sores, where the evidence is promising. It's generally easy on the stomach at normal doses, but anyone taking a 5-HT4 agonist should check with us first.

If you're pregnant or breastfeeding, a quick conversation with your doctor or pharmacist will help you decide if it's right for you.

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 Dec 21, 2024.

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

At a glance

General information

Key facts about Lysine 400, straight from the product label.

Brand ProCaps Laboratories
Barcode (UPC) 141232
Net contents 360 Easy-To-Swallow Capsule(s)
Market status On market
Date entered into DSLD Dec 21, 2024
DSLD ID 320143
Product type Amino Acid/protein
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), No Allergies, Gluten Free, Dairy Free, Sugar Free
From the label
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 Lysine 400 by ProCaps Laboratories, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
360
UPC/BARCODE
141232
IngredientAmount% DV
L-Lysine400 mg--

Other ingredients: Gelatin

Tap any ingredient to jump to its full detail below.

Label statements
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 Consume one capsule daily. You can increase your intake based upon your needs and as guided by your health care provider.

General Statements

For questions about the use of this product call 800.800.1200.

Questions? Reorders? 800.800.1200 procaps.com Andrew Lessman

Formulation

Since 1979, unsurpassed purity, quality and efficacy. 100% Solar production Zero-carbon footprint

100% Solar

Contains no additives or common allergens Contains no milk, soy, yeast, corn, wheat, gluten, sodium, salt, sugar, fat, cholesterol, color, preservative, common allergens, genetically modified (GMO) ingredients or manufacturing additives.

Brand IP Statement(s)

Copyright 2022 ProCaps Laboratories

Formula

Immune supportive amino acid

Lysine 400 is a pure, natural source of the essential amino acid L-lysine. Lysine is among the most frequently supplemented amino acids, because of its established role in immune system support, as well as its central role in fat burning and energy metabolism. Lysine is one of only nine amino acids referred to as essential because it cannot be produced by the body and is only available through diet or supplementation. Lysine is vital for the growth and development of all body tissues and is central to the production of energy, since it is a precursor to acetyl CoA synthesis - a critical component of all energy metabolism. Additionally, Lysine is also required to create carnitine, which is necessary for all fat metabolism. Lysine also plays an important structural role in the formation of collagen - the basic protein structure of skin, bones, joints and connective tissue (tendons, ligaments and cartilage). In short, Lysine is among the most important of our body's amino acids playing a multitude of critical roles in the most vital systems in our body.

FDA Statement of Identity

Dietary Supplement

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.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Lysine 400 by ProCaps Laboratories label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Lysine 400 label

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)
What’s inside

The Ingredients in Lysine 400 by ProCaps Laboratories

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 container360 Amounts shown are per serving.

L-Lysine

Interacts with
1 drug
400 mg per serving Form: L-Lysine Hydrochloride

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 & interactions

Other (inactive) ingredients: Gelatin. These complete the product’s ingredient list but are not active constituents.

Interaction report

Lysine 400 by ProCaps Laboratories Drug Interactions

Want to check YOUR meds against Lysine 400?

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 checker
1Drugs
1 Minor

Ingredients driving the most interactions

L-Lysine 1

Individual Drug Interactions

The ingredients in Lysine 400 interact with 1 drug. Click any drug to see the details.

1 of the 1 ingredient in Lysine 400 interact with drugs. Each result below shows which ingredient is responsible. L-Lysine

Each ingredient & the kinds of drugs it affects

For each ingredient in Lysine 400 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-Lysine1 drug type · 1 drug

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.

Likelihood Unlikely Evidence D
L-Lysine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Lysine 400, from the product label.

ProCaps Laboratories

See all ProCaps Laboratories products
Name
ProCaps Labs
City
Henderson
State
NV
ZipCode
89011
Phone Number
800.800.1200
Web Address
ProCaps.com
Pharmacist Counseling Corner

Lysine 400 by ProCaps Laboratories: Common Questions

Does Lysine 400 by ProCaps Laboratories interact with any medications?
Yes. Based on its ingredients, Lysine 400 has a known interaction with 1 medication. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Lysine 400 contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Will lysine really help my cold sores?
The evidence suggests it's possibly effective for cold sores. That means some research supports it, but we don't have enough data to say it works for everyone. It's worth trying if you're prone to them, but results vary from person to person.
What are the side effects?
Most people tolerate lysine well. The most common side effects are belly pain, diarrhea, and indigestion. High doses are more likely to cause stomach upset, so stick to typical amounts.
Can I take this if I'm pregnant?
Lysine from food is fine, but we don't have enough data on supplement safety during pregnancy. Talk to your doctor before taking it—they know your situation and can give you personalized advice.
Is it safe while breastfeeding?
There isn't enough reliable information on lysine supplements during breastfeeding, so caution is advised. Check with your doctor or pharmacist to decide what's best for you and your baby.
Does lysine work for anything other than cold sores?
The evidence is strongest for cold sores. For child growth, pressure ulcers, and diabetic foot ulcers, we don't have enough reliable data to say whether it helps.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Not sure if Lysine 400 is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

Lysine 400 label
Go deeper

The Full Monographs Behind Lysine 400’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Lysine

Interacts with 1 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 try to prevent or shorten cold sores, but...

Read the full Lysine monograph →
Sources

Sources & How We Checked

Lysine 400'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.

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
  1. 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
  2. McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis 1984;34:366-73.
  3. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol 1984;120:48-51. DOI
  4. 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.
  5. 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
  6. 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
  7. 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.

See these in context on the Lysine monograph →

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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team