Amino Acid
This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer
L-Lysine is an essential amino acid most studied for reducing herpes simplex (cold sore) outbreaks by antagonizing arginine. At 1-3 g/day, it may reduce HSV recurrence frequency and severity. It also supports collagen formation, calcium absorption, and carnitine synthesis.
L-Lysine is most notable for its antiviral properties against HSV. The Griffith et al. (1987) RCT showed significant reduction in herpes recurrence at 3 g/day. The mechanism involves competitive inhibition of arginine, which HSV requires for replication. Beyond antiviral use, lysine supports collagen formation and calcium metabolism. Evidence quality is moderate — many studies are older and relatively small.
L-Lysine is most notable for its antiviral properties against HSV.
| Form | Bioavailability | Best For |
|---|---|---|
| L-Lysine HCl | High | Most common supplemental form; well-absorbed and cost-effective |
| L-Lysine (free form) | High | Standard capsule and tablet formulations |
General recommendation: 1-3 g daily, divided into 2-3 doses
Timing: With meals or on an empty stomach; for HSV, consistent daily dosing is key
| Condition | Recommended Dose | Evidence |
|---|---|---|
| Herpes simplex prevention | 1 g three times daily during outbreaks; 500-1000 mg daily for prevention | Moderate |
| Collagen support | 500-1000 mg daily | Moderate |
| Calcium absorption | 400-800 mg daily | Moderate |
Upper limit: 3-6 g/day has been used safely; very high chronic doses may increase cholesterol in rare cases
Safety profile: Generally Safe
Clinical evidence suggests it can. A 1987 RCT found 1 g lysine three times daily significantly reduced herpes simplex recurrence and severity. The mechanism is competitive inhibition of arginine, an amino acid HSV needs to replicate. For prevention, 500-1000 mg daily is commonly used; during active outbreaks, 3 g/day is typical. Results vary between individuals.
They have opposing effects regarding herpes — lysine inhibits HSV replication while arginine may promote it. If taking lysine for cold sore prevention, avoid high-dose arginine supplementation. For general health, moderate amounts of both from food are fine. If using both as supplements, take them at different times of day.
For general health, 500-1000 mg daily is sufficient. For herpes prevention, 1-3 g daily is the studied range. During active cold sore outbreaks, up to 3 g daily in divided doses has been used. The RDA for lysine is about 38 mg/kg body weight, easily met through a diet containing adequate animal protein.