L-Lysine
Research Reliability -
An essential amino acid critical for collagen synthesis, calcium absorption, immune function, and viral suppression.
Appetite
Mood
Sleep
L-Lysine
Description
L-Lysine is an essential amino acid that cannot be synthesized by the body and must be obtained through diet or supplementation. It is a primary building block for collagen production and plays a key role in calcium absorption and retention, supporting bone health. Lysine is also well known for its antiviral properties, particularly against the herpes simplex virus, where it competes with arginine for viral replication pathways. Vegans and vegetarians may be at particular risk for lysine deficiency given its lower concentration in plant-based protein sources compared to animal foods.
Effects
First days
most useful at the first tingle of a cold sore
Weeks 1–2
acute antiviral support during an outbreak
Ongoing
low-dose maintenance for the prone
How it Feels
For cold-sore-prone people, taken at the first tingle it can blunt an outbreak within a day or two, which is its most felt use. As a daily preventive it is quiet and unremarkable. Otherwise there is little to notice.
Usage
Entry Dose
500mg
Standard Dose
1000–1500mg
Max Dose
3000mg
Onset
1–2 weeks (acute antiviral); weeks (collagen)
Combinations
Pairs well with
Synergistic
Vitamin C — lysine + C is the classic Pauling protocol for collagen and cardiovascular health
Zinc — combined antiviral support; zinc directly inhibits viral replication
Proline — lysine and proline are the two key amino acids in the collagen triple helix
Avoid combining
Contraindicated
High-dose arginine — lysine and arginine compete for absorption; lysine suppresses arginine
Calcium (very high lysine doses) — very high lysine intake may increase urinary calcium excretion
Biomarkers to Track
Subjective
(Daily)
Cold sore outbreak frequency
Skin healing speed (1–10)
Mood and anxiety score
Objective
(Quarterly)
Serum lysine level (specialty)
Herpes outbreak frequency log
Plasma calcium level
Very safe.
People with kidney disease should moderate high doses.
Taking it only daily as prevention, when its strongest use is at the first tingle of a cold sore.
Preliminary (limited / small human data)
Evidence for reducing herpes simplex recurrence is mixed across trials and generally low quality.
Mailoo VJ, Rampes S (2017). Integrative Medicine (Encinitas). Review (lysine for herpes simplex prevention). PMID: 29844853.