Natural Health Products

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General Information

Lysine is one of the essential amino acids. This means that although the body needs lysine to make proteins, it cannot manufacture its own lysine. The body must get the lysine it needs from sources like meat, fish, dairy, eggs, and plants like soy and other legumes.

Common Name(s)
L-lysine, lys, lysine
Scientific Name(s)
L-2,6-diaminohexanoic acid
How is this product usually used?

Lysine can be obtained from foods and supplements (for people using lysine for medical purposes) and it is available in capsules, tablets, chewable tablets/gummies, strips, powders, and liquids.

The recommended dietary allowance (RDA) of lysine is 38 mg/kg of body weight per day for adults over 19 years old. The RDA is increased during pregnancy and breast-feeding to 51 mg/kg/day and 52 mg/kg/day, respectively.

Typically, 1,000 mg orallyorallyto be taken by mouth (swallowed) (by mouth) 1 to 3 times per day is recommended to reduce the recurrence of HSV infection (e.g., cold sores).

The RDA of lysine is 89 mg/kg/day for infants 7 to 12 months old, 58 mg/kg/day for children 1 to 3 years old, and 40-46 mg/kg/day for children 4 to 18 years old.

Do not use lysine for more than 6 months at doses higher than 300 mg per day without checking with your health care provider.

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What is this product used for?

Lysine is used orallyorallyto be taken by mouth (swallowed) (by mouth):

  • as an essential amino acid for the maintenance of good health
  • to help reduce the recurrence of HSV infection (e.g., cold sores)
  • to help in formation of collagen

Lysine has also been used to:

  • treat metabolic disorders
  • treat lysine deficiency
  • increase calcium absorption
  • manage pain
  • manage type 2 diabetes
  • improve athletic performance
  • promote growth in children
  • reduce stress and anxiety

There is strong evidence that lysine supplements are effective in treating lysine deficiency. However, the use of lysine to prevent or treat HSV infections such as cold sores has mixed results, and further studies are needed to support its use in this condition and other above-mentioned uses.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

Lysine is likely safe when used at recommended doses (<3000mg/day)  for up to 6 months. If you are unsure about the dose you are currently taking, please consult with your health care practitioner. Side effects may include cramping, stomach pain, and diarrhea. Rarely, it can cause gallstones, kidney and liver damage.

Lysine may increase absorption of calcium and decrease the loss of calcium in urine. To avoid calcium toxicity, check with your health care provider before using lysine if you are taking calcium supplements.

Lysine may increase the risk of bleeding and therefore should be used with caution by people with bleeding disorders. It may interact with medications that can increase this risk, such as anticoagulant medications (e.g., warfarin, heparin) and anti-platelet medications (e.g., clopidogrel).

Lysine may increase the risk of low blood sugar if you take medication for diabetes.

Speak to your health care provider before using lysine if you have:

  • bleeding disorders
  • diabetes
  • high cholesterol levels
  • a modified diet (e.g., low protein)
  • pancreas problems
  • thymus disorders
  • a weakened immune system

Use of lysine during pregnancy and breast-feeding is not recommended for purposes other than lysine deficiency. Consult a health care practitioner if you are considering taking lysine while pregnant or breast-feeding.

Do not use lysine if you:

  • are allergic to lysine
  • have liver problems
  • have kidney problems

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider.  Tell your health care provider about any natural health products you may be taking.

  1. Health Canada. Licensed Natural Health Products. Lysine. (accessed 2 July 2014)
  2. Lysine (professional monograph). Natural Standard – The Authority on Integrative medicine. (Accessed online 2 July 2014)
  3. Lysine. Natural Medicines Comprehensive Database. (Accessed online 10 Feb 2012)
  4. Lysine monograph. Lexicomp. (Accessed 2 July 2014)

All material copyright MediResource Inc. 1996 – 2020. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.