The most predominant benefit of L-Lysine Mono HCL Powder is for treatment of mouth and genital lesions caused by herpes simplex virus, as well as shingles caused by herpes zoster viruses. Taking L-lysine can speed recovery time and reduce the chance of recurrent breakouts of herpes infection. It also increases the intestinal absorption of calcium and eliminates its excretion by the kidney, suggesting that it might be helpful in osteoporosis.