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Latest Edit: Hector 2014-03-17 (EDT)

See Also Amino Acids

L-lysine is an essential amino acid and therefore must be supplied in the diet. L-lysine's popularity as a supplement began as some studies found it to have antiviral action against herpes simplex virus.[1].

Food Sources

The following foods have the highest concentration of L-lysine.


The following are the primary uses for L-lysine: [1]

  • Herpes Simplex Virus: Several clinical studies show that L-lysine is beneficial in preventing and shortening outbreaks of herpes simplex infections.
  • Osteoporosis: One study has shown that L-lysine increases intestinal absorption and improves renal conservation of calcium thus it has been considered in the treatment of osteoporosis. More research is needed in this area.

Prescribing Considerations

  • L-lysine is available in capsule, powder, and tablet form.
  • No RDA has been established for L-Lysine. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.


  • General Adverse Effects: High doses (>10-15g/day) may cause gastrointestinal symptoms such as nausea, abdominal cramps, and diarrhea.
  • Pregnancy Breastfeeding: One should only consider using supplemental L-lysine at this time if the diet is low in this amino acid.
  • Contraindications: L-lysine supplementation is contraindicated in those with the rare genetic disorder hyperlysinemia/hyperlysinuria.
  • Precautions: Proteins high in L-lysine relative to L-arginine such as casein are associated with elevated cholesterol. Therefore, individuals with hypercholesterolemia should be cautious of this if interested in supplementing with L-lysine. Those with hepatic and renal failure should also exercise caution if using supplemental L-lysine.
  • Drug Interactions: None are expected.

Nutrient Interactions

  • Arginine - Foods high in arginine such as raisins, chocolate, seeds, carob, and nuts, may decrease the ability of L-lysine to prevent or reduce cold sore outbreaks.[2]
  • Calcium - Concomitant use of calcium and L-lysine may increase calcium absorption [1]


  1. 1.0 1.1 1.2 Hendler Sheldon S, Rorvik David (Editors) (2008) PDR for Nutritional Supplements, Medical Economics Company Inc.
  2. Griffith Winter H (2000) Vitamins, Herbs, Minerals & Supplements: The Complete Guide MJF Books.