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L-Lysine
Competes with arginine to suppress cold sore outbreaks while supporting collagen synthesis, immune function, and calcium absorption.
What the evidence says
L-Lysine appears to help in 7 of 9 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1987–2025 with a typical study size of 60 participants.
Based on 24 studies · 2 meta-analyses · 13 RCTs · 3,340 total participants
Confidence
HighWhat the studies found
By outcome
L-Lysine has an evidence score of 7/10 — strong evidence based on 24 indexed studies, including 1 meta-analysis. Competes with arginine to suppress cold sore outbreaks while supporting collagen synthesis, immune function, and calcium absorption.
The commonly studied dose of L-Lysine is 500-3000mg daily; higher for active outbreaks. Research points to an estimated optimal dose around 1500mg, with a minimum effective dose near 500mg. Individual response varies — start low and adjust.
The best time to take L-Lysine is between meals. It can be taken on an empty stomach. L-lysine is an essential amino acid that competes with L-arginine for absorption via the shared y+ cationic amino acid transporter system in the intestine.
Carnosine
Likely helpsBlocks protein glycation and buffers muscle pH, supporting longevity, exercise performance, and cognitive function.
Marine Collagen
Likely helpsType I collagen from fish with smaller peptide size for superior absorption — proven benefits for skin hydration and wrinkle reduction.
Last reviewed May 2026 · evidence from 40 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
L-Lysine is an essential amino acid that must be obtained from diet or supplements. It's a key building block for collagen synthesis and plays important roles in immune function, calcium absorption, and hormone production. Lysine is best known for its ability to prevent and reduce cold sore outbreaks by competing with arginine, which HSV needs to replicate. It's often deficient in vegetarian diets as grains are low in lysine.
Competes with arginine to inhibit HSV
Essential for collagen production
Enhances calcium uptake
How L-Lysine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
500-3000mg daily; higher for active outbreaks
Loading: For active cold sores: 3000-6000mg/day in divided doses
Can be taken without food
| Form | Type |
|---|---|
| 💊L-Lysine HCl (capsules or powder) | Recommended |
| 💊L-Lysine tablets | Alternative |
L-Lysine HCl is standard and well-absorbed. Available as powder, capsules, or tablets.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Best absorbed on empty stomach. Reduce arginine-rich foods (nuts, chocolate, seeds) during outbreaks.
Safety profile based on systematic review of 71 studies (n=2619). Risk analysis showed no statistically significant increase in GI symptoms (RR 1.02, 95% CI 0.96-1.07, p=0.49). Adverse events were mainly subjective GI symptoms. Short-term use up to 6g appears safe.
Reduced frequency and severity of outbreaks
Supports skin, bone, and tissue health
General immune function support
Well-studied for HSV prevention; effective at 1-3g/day
May need supplementation as grains are low in lysine
May enhance calcium absorption
Tip: Take with food if needed; reduce dose
Tip: Reduce dose
L-Lysine is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are GI upset, diarrhea. Use caution if any of these apply to you: Lysinuric protein intolerance (rare genetic disorder).
Taurine
Likely helpsConcentrated in heart, brain, and muscle — emerging longevity data alongside proven benefits for sleep, cardiovascular function, and recovery.
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