Lysine appears to suppress the clinical manifestations of herpesvirus infection. 45 patients with frequently recurring herpes infection were given 312–1,200 mg of lysine daily in single or multiple doses. The clinical results demonstrated a beneficial effect from supplementary lysine in accelerating recovery from herpes simplex infection and suppressing recurrence. Tissue culture studies have demonstrated an enhancing effect on viral replication when the amino acid ratio of arginine to lysine favors arginine. The opposite, preponderance of lysine to arginine, suppresses viral replication and inhibits cyto-pathogenicity of herpes simplex virus. The codons characterizing herpes simplex DNA apparently specify production of viral capsids at the expense of host cell histones.

In the studies conducted, arginine deficiency suppressed herpes simplex virus replication in tissue culture. Lysine, an analog of arginine, as an antimetabolite, antagonized the viral growth-promoting action of arginine. The in vitro data may be the basis for the observation that patients prone to herpetic lesions and other related viral infections, particularly during periods of stress, should abstain from arginine excess and may also require supplemental lysine in their diet.

A double-blind, placebo-controlled, multicenter trial of oral L-lysine monohydrochloride for the prevention and treatment of recurrent herpes simplex (HSV) infection was conducted. The treatment group was given L-Lysine monohydrochloride tablets (1,000 mg L-lysine per dose) 3 times a day for 6 months. A total of 27 (6 male and 21 female) subjects on L-lysine and 25 (6 male and 19 female) subjects on placebo completed the trial. The L-lysine treatment group had an average of 2.4 (p < 0.05) less HSV infections, symptoms were significantly (p < 0.05) diminished in severity and healing time was significantly reduced (p < 0.05). L-Lysine appears to be an effective agent for reduction of occurrence, severity and healing time for recurrent HSV infection.