L-Lysine

A dose-dependent supplement — the popular 500mg dose is likely too low to match the research

An essential amino acid the body can't produce

Cold sore research shows a clear dose threshold

Important: These statements have not been evaluated by the FDA. This information is not intended to diagnose, treat, cure, or prevent any disease. Always consult your physician before starting any supplement.

Overview

L-Lysine is an essential amino acid — meaning the body can't produce it and it must come from food or supplements. It's a building block for protein synthesis, plays a role in collagen formation and calcium absorption, and is most widely known in the supplement world for one specific, long-studied use case: suppressing the frequency and severity of recurrent herpes simplex (cold sore) outbreaks.

The lysine-and-cold-sores research has been around since the 1980s, and it's a genuinely useful case study in why dose matters as much as the ingredient itself. The proposed mechanism involves lysine competing with arginine, an amino acid the herpes virus needs to replicate — but the clinical trials showing benefit consistently used considerably higher doses than what's found in a typical single capsule sold for this purpose.

Potential Benefits

Cold Sore Frequency & Severity

A classic 6-month double-blind trial found the lysine group averaged 2.4 times fewer herpes outbreaks with diminished symptom severity, at a dose of 3g/day.

Collagen Formation Support

Lysine is one of the amino acids involved in collagen cross-linking, relevant to skin, tendon, and connective tissue structure.

Calcium Absorption

Involved in enhancing intestinal calcium absorption and reducing calcium excretion in some research contexts.

Protein Synthesis Building Block

As an essential amino acid, adequate lysine intake supports general protein synthesis throughout the body.

Typical Dosage

Dose Studied for Cold Sores

3g per day or more

Studies below 1g/day generally showed no meaningful effect without also restricting arginine intake

Common Retail Dose

500mg per capsule

Likely below the threshold shown to work in the strongest trials — check total daily intake, not just per-capsule amount

Pro Tips

Check the total daily dose across all capsules — a single 500mg pill is unlikely to match what worked in trials
Some protocols pair higher-dose lysine with a lower-arginine diet (fewer nuts, chocolate, seeds) during outbreaks
Consistency matters — the positive trials used daily supplementation over months, not just during an active outbreak
Set expectations honestly: this is a mixed-evidence area, not a guaranteed fix

Research Snapshot

A 2017 review of the lysine-and-herpes-simplex literature concluded that supplementation at doses below 1g/day was generally ineffective for prophylaxis or treatment unless combined with a low-arginine diet, while doses of 3g/day or more appeared to improve patients' subjective symptom experience across the available trials. This dose-response pattern is consistent with the classic 6-month, double-blind, multicenter trial that found the 3g/day lysine group averaged 2.4 times fewer HSV outbreaks than placebo, with reduced symptom severity and faster healing.

Source: Mailoo & Rampes, Integrative Medicine (2017)

How L-Lysine Compares

Ingredient	Best For	Key Difference
L-Lysine	Cold Sore Suppression	Requires a meaningfully higher dose than typical capsules provide
Collagen	Skin & Joint Support	A finished protein source containing lysine among other amino acids
L-Arginine	Nitric Oxide, Circulation	The amino acid lysine is thought to compete against for herpes suppression
Glycine	Sleep, Collagen Synthesis	Different amino acid with its own distinct research base

These are the most common comparisons our customers ask about in-store.

Popular Stacks with L-Lysine

Cold Sore Support Stack

L-Lysine + Vitamin C + Zinc

Pairs the dose-appropriate lysine strategy with general immune-support basics

Skin & Connective Tissue Stack

L-Lysine + Collagen + Vitamin C

Vitamin C is a required cofactor for the collagen cross-linking process lysine supports

Bone Support Stack

L-Lysine + Calcium + Vitamin D3

Rounds out lysine's role in calcium absorption with the primary bone-support nutrients

Frequently Asked Questions

Does L-Lysine actually help with cold sores?

The evidence is genuinely mixed and dose-dependent. A 2017 review found that doses under 1 gram per day were generally ineffective, while doses of 3 grams or more per day showed improvement in symptom severity in some studies. A classic 6-month double-blind trial found the treatment group averaged 2.4 times fewer outbreaks. The honest takeaway: most standard 500mg lysine products sold for cold sores are likely underdosed relative to what showed any effect in trials.

What dose of lysine is actually used in the research?

Studies showing a meaningful effect on herpes outbreak severity generally used 3 grams or more per day, often split into multiple doses, sometimes alongside a low-arginine diet. This is considerably higher than the 500mg-1000mg commonly found in single capsules marketed for cold sores.

Does lysine interact with arginine?

The proposed mechanism behind lysine's effect on herpes involves competing with arginine, an amino acid the herpes virus needs to replicate. This is why some protocols pair higher-dose lysine with reduced arginine intake (limiting nuts, chocolate, and seeds) rather than using lysine alone.

Sources & References

1. Mailoo, V.J., & Rampes, S. (2017). Lysine for herpes simplex prophylaxis: a review of the evidence. Integrative Medicine (Encinitas), 16(3), 42–46.

2. Griffith, R.S., Walsh, D.E., Myrmel, K.H., Thompson, R.W., & Behforooz, A. (1987). Success of L-lysine therapy in frequently recurrent herpes simplex infection: treatment and prophylaxis. Dermatologica, 175(4), 183–190.

All references are peer-reviewed studies or position stands from reputable organizations.