Amino Acid
L-Lysine
Also known as: Lysine, L-Lysine HCl, Lysine Monohydrochloride
Essential amino acid important for protein synthesis, collagen formation, calcium absorption, and immune function, particularly noted for antiviral properties.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every L-Lysine product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Pure Encapsulations L-Lysine | 94 A | $0.17 |
| 2 | BulkSupplements L-Lysine HCl Capsules | 92 A | $0.19 |
| 3 | Thorne Lysine | 91 A | $0.25 |
| 4 | Life Extension L-Lysine | 91 A | $0.09 |
| 5 | Solgar L-Lysine | 91 A | $0.14 |
| 6 | Nature Made L-Lysine 1000 mg Tablets | 90 A | $0.16 |
| 7 | Thorne MediClear-SGS™ - Vanilla | 86 A- | $2.10 |
| 8 | Vital Nutrients Lysine 500mg | 86 A- | $0.48 |
| 9 | Thorne Amino Complex - Travel Packs - Berry | 85 A- | $1.20 |
| 10 | Thorne Amino Complex - Travel Packs - Lemon | 85 A- | $1.20 |
| 11 | Thorne Amino Complex - Berry | 84 A- | $1.47 |
| 12 | Thorne Amino Complex - Lemon | 84 A- | $1.47 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much L-Lysine should I take?
The typical range is 500-3000 mg daily. Safe for long-term use
When should I take L-Lysine?
Between meals or with meals. Either way.
Which form of L-Lysine is best?
Free form — Pure L-lysine. Other forms in the catalog: L-lysine monohydrochloride, L-lysine HCl.
Is L-Lysine safe?
Commonly reported: GI upset at high doses. Caution with kidney disease at high doses
Which L-Lysine supplement scores highest?
Pure Encapsulations L-Lysine, at 94/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
1000 mg / dayL-Lysine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
L-Lysine dosage reference →Primary uses
- Cold sore prevention
- Protein synthesis
- Collagen support
- Calcium absorption
How it works
- Competes with arginine for viral replication
- Essential for collagen synthesis
- Supports carnitine production
Dosage
- Typical range
- 500-3000 mg daily
- Timing
- Between meals or with meals
- With food
- Either way
- Duration
- Safe for long-term use
- Special populations
- Those prone to cold sores
Forms
- Free form· 95/100
- L-lysine monohydrochloride· 90/100
- L-lysine HCl· 90/100
Safety
Common side effects
- GI upset at high doses
Products containing L-Lysine
Top-scoring supplements in our catalog that list L-Lysine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Good evidence for cold sore prevention, protein synthesis
Grade B: Some human trials support key claims; further confirmation needed.
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.