Lysine Overview

Lysine is an essential amino acid, one that you need to get from food. Some evidence suggests that supplemental lysine may be able to help prevent herpes infections (cold sores and genital herpes).

Most people need about 1 g of lysine per day. The requirement may be greater for athletes and people recovering from major injuries, especially burns. The richest sources of lysine are animal proteins such as meat and poultry, but it is also found in dairy products, eggs, and beans.

A typical therapeutic dosage of lysine for herpes infections is 1 g three times daily. You can take this as a regular part of your diet in hopes of preventing herpes flare-ups, or, perhaps, at the first sign of an attack. Although the evidence isn't strong, there may be some advantage to restricting your intake of foods that contain a lot of arginine, such as chocolate, peanuts, other nuts and seeds, and, to a lesser extent, wheat.

When taken in sufficient doses, it appears that regular use of lysine supplements might be able to reduce the number and intensity of herpes flare-ups. ¹ One double-blind, placebo-controlled study followed 52 participants with a history of herpes flare-ups. ² While receiving 3 g of L-lysine every day for 6 months, the treatment group experienced an average of 2.4 fewer herpes flare-ups than the placebo group—a significant difference. The lysine group's flare-ups were also significantly less severe and healed faster.

Another double-blind placebo-controlled crossover study on 41 subjects also found improvements in the frequency of attacks. ³ Interestingly, this study found that 1,250 mg of lysine daily worked, but 624 mg did not.

Other studies, including one that followed 65 individuals, found no benefit, but they used lower dosages of lysine. ⁴ Although some are promising, none of these studies are large enough to give conclusive answers. At this point, more evidence is needed to determine whether lysine is effective for preventing herpes simplex.

Many people use lysine in a different way—they take it at the onset of a herpes attack. However, a double-blind, placebo-controlled study evaluating this method found no benefit. ⁵ (Consider using the herb lemon balm instead.)

1. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr. 16(1):7-21.
2. Griffith RS, Walsh DE, Myrmel KH, Thompson RW, Behforooz A. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 175(4):183-90.
3. McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis. 34(4):366-73.
4. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol. 120(1):48-51.
5. Milman N, Scheibel J, Jessen O. Failure of lysine treatment in recurrent herpes simplex labialis [letter]. Lancet. 1978;2:942.