Evidence supporting the use of: L-lysine
For the health condition: Cold Sores

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Synopsis

Source of validity: Scientific
Rating (out of 5): 3

L-lysine is an essential amino acid that has been studied for its potential to prevent and treat cold sores, which are caused by the herpes simplex virus (HSV), most commonly HSV-1. The rationale for its use is based on the interaction between lysine and another amino acid, arginine. HSV requires arginine for replication; lysine is thought to act as a competitive inhibitor, reducing arginine's availability and thereby slowing viral replication. Several clinical studies have evaluated lysine supplementation for cold sore management. A meta-analysis of randomized, placebo-controlled trials indicates that lysine, when taken as a preventive supplement (typically 1,000 mg/day or greater), may reduce the frequency, severity, and healing time of cold sore outbreaks in some individuals. However, not all studies have shown significant benefit, and results can be inconsistent depending on dosage, study design, and population. The evidence is stronger for preventive use rather than for treatment of acute outbreaks. Lysine is generally considered safe at recommended doses, though high doses may cause gastrointestinal upset in some people. Clinical guidelines do not universally endorse lysine for HSV, but it remains a popular over-the-counter approach. While scientific evidence exists and supports a moderate effect, more research is needed to establish optimal dosing and clarify the populations most likely to benefit.

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Other health conditions supported by L-lysine

Cold Sores
Herpes