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L-Lysine

Immune · cold-sore support · collagen

Moderate evidenceVegan104 studies on PubMedRead the research
Written to our editorial standards · reviewed against published research· Updated 30 May 2026
Last reviewed: May 30, 2026

L-Lysine: Immune · cold-sore support · collagen. An essential amino acid the body cannot make, popular for cold-sore support, collagen formation, and immune resilience. Standard dose 1,000 mg, taken in the morning, about $9/month. Evidence rating: moderate evidence.

Where to buy

NOW Foods L-Lysine 1000 mg
Recommended
NOW Foods, L-Lysine
1,000 mg · Morning · ~$9/month

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All product options

NOW Foods L-Lysine 1000 mgBestseller
L-Lysine 1000 mg
NOW Foods
100 tablets · $9 · ★ 4.8
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Doctor's Best L-LysineBest Value
L-Lysine
Doctor's Best
180 veg caps · $13 · ★ 4.7
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Solgar L-Lysine 1000 mgPremium
L-Lysine 1000 mg
Solgar
100 tablets · $14 · ★ 4.7
Buy on iHerb →
Nature's Way L-LysinePremium
L-Lysine
Nature's Way
100 capsules · $10 · ★ 4.6
Buy on iHerb →

What is L-Lysine?

L-lysine is an essential amino acid, meaning you must get it from food or supplements. It is needed to build collagen and to absorb calcium, and it is best known for managing cold-sore (herpes simplex) outbreaks, where it appears to compete with the amino acid the virus needs to copy itself. Several trials report that regular lysine reduces how often and how severely these recurrences happen, though results are not uniform. It is also of interest for immune and bone support and is very well tolerated. People who eat little animal protein or legumes, or who train hard, may fall short. A common approach is 1 g daily for maintenance and more during an active outbreak.

An essential amino acid the body cannot make, popular for cold-sore support, collagen formation, and immune resilience.

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Common questions

What is L-Lysine?
L-lysine is an essential amino acid, meaning you must get it from food or supplements. It is needed to build collagen and to absorb calcium, and it is best known for managing cold-sore (herpes simplex) outbreaks, where it appears to compete with the amino acid the virus needs to copy itself. Several trials report that regular lysine reduces how often and how severely these recurrences happen, though results are not uniform. It is also of interest for immune and bone support and is very well tolerated. People who eat little animal protein or legumes, or who train hard, may fall short. A common approach is 1 g daily for maintenance and more during an active outbreak.
What is L-Lysine used for?
Immune · cold-sore support · collagen. An essential amino acid the body cannot make, popular for cold-sore support, collagen formation, and immune resilience.
What is the standard dose of L-Lysine?
1,000 mg, typically taken in the morning. Approximate cost is $9 per month.
How strong is the evidence for L-Lysine?
Moderate evidence for its primary uses. See the full study list on the research page.

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