Lysine is used to prevent and treat cold sores, and some evidence suggests it can increase athletic performance, lower blood sugar in diabetic patients, reduce stress and treat canker sores, according to WebMD. Depending on the condition, individuals may take lysine by mouth or apply it to the skin.
Studies suggest lysine can treat cold sores when applied to the skin as a cream or taken by mouth, states WebMD. However, it may not prevent recurrence or reduce the severity of the sores. The substance may work by halting the spread of the herpes virus. Some early research also suggests a daily dose of 4,000 milligrams of lysine decreases the length of canker sores, while 500 milligrams daily can prevent them. Although the research concerning lysine and blood sugar is conflicted, early studies indicate that taking the supplement twice daily can reduce blood sugar in diabetic patients.
Early research also suggests that consuming bread containing added lysine can reduce anxiety in men and reduce stress in women, explains WebMD. As of 2015, more research is needed to rate the effectiveness of lysine for boosting athletic performance. Individuals who are pregnant or breastfeeding should speak with a doctor before taking lysine.