Amino acids
L-lysine
Also called: lysine
An essential amino acid.
- Why people take it
- Cold sores (herpes), anxiety.
- What the evidence says
- Mixed evidence for preventing cold sores.
- How it is usually taken
- Usually 1 to 3 g a day for cold sore prevention.
- Be careful
- Generally safe; high doses can cause stomach upset. Caution with kidney disease.
- Medicines it can interact with
- No important medicine interactions are known, but tell your doctor and pharmacist about every supplement you take.
Other amino acids
Common questions
What is L-lysine?
An essential amino acid.
Why do people take L-lysine?
Cold sores (herpes), anxiety.
Does L-lysine work?
Mixed evidence for preventing cold sores.
How much L-lysine do people take?
Usually 1 to 3 g a day for cold sore prevention.
Is L-lysine safe?
Generally safe; high doses can cause stomach upset. Caution with kidney disease.
Does L-lysine interact with medicines?
No important medicine interactions are known, but tell your doctor and pharmacist about every supplement you take.
Sources and further reading
Last reviewed 31 October 2026. Written by Satya Babu.
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