Reviewed on 8/24/2021

What Is Lysine and How Does It Work?

Lysine is an herbal supplement used for athletic performance enhancement, or treatment for cold sores (herpes simplex libialis) and elevated pH (metabolic alkalosis).

  • Lysine is possibly effective for cold sores (herpes simplex labialis) treatment.
  • Lysine is available under the following different brand names: L-lysine and Lysine Monohydrochloride.

What Are Dosages of Lysine?

Dosages of Lysine:

  • Oral
  • Topical

Dosage Considerations – Should be Given as Follows:

Herpes Simplex Labialis

  • 1,000 mg orally daily for 12 months and
  • 1,000 mg orally three times daily 6 months

Topical: (Super Lysine Plus) applied every 2 hours for 11 days

Metabolic Alkalosis (elevated pH levels)

  • 10 grams orally once daily, divided doses for up to 5 days


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What Are Side Effects Associated with Using Lysine?

The side effects of Lysine include:

  • diarrhea
  • abdominal pain
  • chronic kidney (renal) failure
  • inflammation in the kidney (interstitial nephritis)
  • increased calcium absorption

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Lysine?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Lysine has no known severe interactions with any drugs.
  • Lysine has no known serious interactions with any drugs.
  • Lysine has no known moderate interactions with any drugs.
  • Lysine has no known mild interaction with other drugs.

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

What Are Warnings and Precautions for Lysine?


  • This medication contains lysine
  • Do not take L-lysine and Lysine Monohydrochloride if you are allergic to lysine or any ingredients contained in this drug
  • Keep out of reach of children
  • In case of overdose, get medical help or contact a Poison Control Center immediately


  • Avoid taking large amounts of calcium and lysine at the same time. Lysine can increase how much calcium the body absorbs. Taking calcium along with lysine can increase the amount of calcium in the body.

Effects of Drug Abuse

  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Lysine?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Lysine?"


  • Kidney disease

Pregnancy and Lactation

  • Avoid the use of lysine during pregnancy
  • Avoid the use of lysine when breastfeeding


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