Lysine
L-Lysine
L-Lysine is an essential amino acid that cannot be synthesized by the human body and must be obtained through diet or supplementation. It is primarily used to prevent and reduce the frequency of herpes simplex virus (HSV-1 and HSV-2) outbreaks, support collagen synthesis, and enhance calcium absorption. Supplementation is also common among athletes and individuals with restricted diets (e.g., vegans) to meet protein synthesis demands.
Mechanism of Action
Lysine inhibits herpes simplex virus replication by competitively antagonizing arginine, an amino acid required for viral replication, thereby reducing outbreak frequency and severity. It plays a critical structural role in collagen cross-linking by serving as a substrate for lysyl oxidase, an enzyme essential for stabilizing collagen and elastin fibers. Additionally, lysine facilitates intestinal calcium absorption and reduces urinary calcium excretion, partly through its interaction with calcium transport proteins in the gut.
Evidence by Health Goal(11 goals)
Dosing Protocols
On empty stomach or between meals for best absorption
For HSV outbreak prevention, 1000mg daily is commonly used as maintenance; doses up to 3000mg/day are used during active outbreaks. For general supplementation or collagen support, 500-1000mg/day is sufficient. Split doses across the day at higher amounts to improve tolerability.
Safety & Side Effects
L-Lysine has an excellent safety profile at recommended doses of 500–3000mg/day and is well-tolerated by most healthy adults for long-term use. Individuals with kidney disease, liver disease, or a history of hyperlysemia (a rare metabolic disorder) should use caution and consult a healthcare provider before supplementing.
Possible Side Effects
- !Gastrointestinal discomfort including nausea, cramps, and diarrhea at doses above 3g/day
- !Loose stools or diarrhea with prolonged high-dose use
- !Abdominal pain or bloating at high doses
- !Increased risk of gallstones with very high long-term intake (animal data; human risk unclear)
- !Elevated cholesterol levels reported in some animal studies at supraphysiological doses
- !Potential worsening of kidney function in individuals with pre-existing renal impairment at high doses
- !Rare hypersensitivity or allergic reactions
Interactions
- -May enhance calcium absorption - monitor calcium levels if taking supplemental calcium concurrently
- -High-dose lysine may theoretically potentiate nephrotoxic effects of aminoglycoside antibiotics (e.g., gentamicin) - avoid combination in renal-compromised patients
- -Competes with arginine for intestinal absorption - concurrent high-dose arginine supplementation may reduce lysine efficacy for HSV suppression
- -May modestly increase absorption of calcium-based antacids - use with awareness if managing hypercalcemia
- -No significant interactions with common medications at standard doses, but use caution with drugs that affect renal tubular transport of amino acids
Cost & Where to Buy
L-Lysine is widely available as an over-the-counter supplement at very low cost. Bulk powder is the most economical option (~$5-8/month), while branded capsules or tablets range higher. Price varies by dose, form, and brand quality.
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