Amino Acid
L-Lysine
Also known as: Lysine
Essential amino acid important for collagen synthesis, calcium absorption, and herpes virus suppression.
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 long-term
When should I take L-Lysine?
Any time; increase during outbreak. Optional.
Which form of L-Lysine is best?
Capsules — Common. Other forms in the catalog: Powder.
Is L-Lysine safe?
Commonly reported: GI upset at high doses. Serious warnings: None. Safe
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
- Herpes prevention
- Collagen synthesis
- Calcium absorption
- Immune support
What systematic reviews concluded
Outcomes that systematic reviews of L-Lysine reached a verdict on: 2 with a benefit, 2 with no effect, 2 unclear. Each is quoted from a review and linked to it on PubMed. How these were read.
Reviews found a benefit (2)
“in older women, bicarbonate supplementation and beta-hydroxyethyl butyrate (HMB), lysine, and arginine supplementation have shown positive effects on exercise performance.” PMID 32698345
“strong evidence exists for the use of herbal supplements containing extracts of passionflower or kava and combinations of L-lysine and L-arginine as treatments for anxiety symptoms and disorders.” PMID 20929532
Reviews found no effect (2)
“Integrated analysis of the risk for developing gastrointestinal symptoms revealed that the risk ratio was 1.02 (95% CI, 0.96-1.07; p = 0.49); thus, no significant increase was observed.” PMID 30661148
“the risk ratio was 1.02 (95% CI, 0.96-1.07; p = 0.49); thus, no significant increase was observed.” PMID 30661148
Not enough to say: ornithine levels; postprandial glucose and insulin response.
2 findings from reviews in specific patient groups (such as cancer, pregnancy or surgery) are not shown here.
How it works
- Competes with arginine for herpes virus
- Essential for collagen cross-linking
- Enhances calcium absorption
Dosage
- Typical range
- 500-3000 mg daily
- Timing
- Any time; increase during outbreak
- With food
- Optional
- Duration
- Safe long-term
- Special populations
- Herpes sufferers, vegetarians
Forms
- Capsules
- Powder
Safety
Common side effects
- GI upset at high doses
Contraindications
- None
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
Established for herpes prevention
Grade B: Some human trials support key claims; further confirmation needed.
L-Lysine compared head-to-head
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.