SupplementsAmino acidsImmuneSkin
Lysine is essential and mostly plentiful in a mixed diet. Its supplement fame rests on cold sores (herpes simplex), where the evidence is mixed but points to a dose effect.
Key takeaways
- Lysine is an essential amino acid, also needed for collagen and carnitine synthesis.
- ≥1 g/day may reduce cold-sore (herpes) recurrence; below that, and without limiting arginine, it appears ineffective.1
- Evidence is mixed — helpful for some, not a guaranteed fix.
- Generally safe at supplemental doses.
What it is
Lysine competes with the amino acid arginine, which herpes viruses need to replicate — the proposed basis for its use against cold sores. Dietary lysine is abundant in meat, dairy and legumes.
The evidence
A review of herpes-simplex prophylaxis found that doses of 1 g/day or more reduced recurrence in controlled trials, while lower doses (without an accompanying low-arginine diet) were ineffective — hence the mixed reputation.1
Dose & how to use
For cold-sore prevention, studies use 1–3 g/day. It is not a treatment for active infection in the way antivirals are.
Safety & who benefits
Safe for most; very high long-term intakes are not well studied. Most relevant for people with frequent cold sores.
References
Adult research summary for education, not a prescription. These are food supplements, not treatments for disease.
- Mailoo VJ, Rampes S. Lysine for Herpes Simplex Prophylaxis: A Review of the Evidence. Integr Med (Encinitas) 2017. pmc.ncbi.nlm.nih.gov
This article summarises nutrition and exercise science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.