Lysine

Also known as: l-lysine, lysine hydrochloride

Grade B — Moderate Evidenceamino acidimmuneskin-hair
5003000 mgOn empty stomach or with meals; higher doses for cold sore prevention

L-Lysine is an essential amino acid that competes with arginine for absorption, which underlies its primary clinical application: reducing herpes simplex virus (HSV) outbreaks by limiting the arginine that HSV requires for replication. Clinical trials show reduced frequency and severity of cold sore recurrences at doses of 1-3g/day. Lysine is also critical for collagen synthesis, calcium absorption, and carnitine production, making it relevant for wound healing and connective tissue health.

TL;DR: Essential amino acid best known for cold sore (herpes simplex) prevention. Also evidence for anxiety reduction when combined with arginine. Enhances calcium absorption. Vegans are at higher risk of deficiency.

Last reviewed: 2026-03-12

Quick Facts

Evidence

Grade B

Studies

2

Interactions

1

Forms

1

Evidence Rating: Grade B — Moderate Evidence

Some RCTs with positive results, or strong observational evidence. More research may refine our understanding.

Interaction Warnings

Calcium supplementsLow

Lysine increases calcium absorption — beneficial for bone health, but avoid excess calcium intake.

Important Notes

  • Most effective for cold sore prevention when combined with avoiding high-arginine foods (nuts, chocolate)
  • Vegans may be deficient as lysine is limiting in grains
  • Essential amino acid — body cannot produce it

Clinical Evidence (2 studies)

Lysine for recurrent herpes simplex prophylaxis

Griffith RS et al. (1987) — Dermatologica

L-lysine 1g 3x/day significantly reduced recurrence, severity, and healing time of cold sores

View on PubMed

L-lysine and L-arginine on stress-induced anxiety

Smriga M et al. (2007) — Biomed Res

L-lysine + L-arginine combination reduced cortisol response and trait anxiety in healthy subjects under stress

View on PubMed

Alternatives to Consider

These supplements target similar goals and may be worth considering alongside or instead of Lysine.

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⚕️ Important Disclaimer

This information is for educational purposes only. It is not medical advice. Always consult a healthcare provider before starting any supplement regimen, especially if you take medications or have health conditions.

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