Safety, interactions, side effects

Lysine supplements are considered safe under most circumstances. Patients with severe renal or hepatic disease should avoid increased lysine intake due to the potential for interstitial damage in both organs. Concomitant lysine and calcium supplementation can increase calcium absorption because of decreased renal output, resulting in a metabolic imbalance. The most common side effect of lysine is upset stomach, which tends to occur with higher doses. 

Cost, how supplied, dose

Lysine is typically supplied as a tablet to be taken orally; 1-g lysine tablets cost approximately $10 per 100 tablets. 

The U.S. Department of Agriculture’s recommended dietary allowance of lysine is 38 mg/kg for adults.7 This amount increases to 51 mg/kg in women who are pregnant and lactating. For lysine deficiency, amounts exceeding 6 g per day in divided doses could be prescribed.8

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If using to treat herpetic infections, lysine is recommended daily at 1 to 3 g in single or divided doses for 12 weeks to 12 months.8 The duration would depend on whether treating a single outbreak or attempting to control frequent recurrences. 


Despite a less-than-robust efficacy profile, lysine supplementation is a safe and inexpensive remedy to try in patients with recurrent HSV outbreaks. Possibly of more interest is the role lysine plays in mood disorders. Even if patients are already on prescription medications for depression or anxiety, a discussion about lysine supplementation would be reasonable. Its low side effect profile makes lysine attractive, if not for monotherapy, then possibly as adjunct therapy.

Sherril Sego, FNP-C, DNP, is a primary-care nurse practitioner at the Department of Veterans Affairs Medical Center in Kansas City, Mo. 


  1. The Amino Acids Guide. Lysine. Available at

  2. Gaby AR. Natural remedies for herpes simplex. 
Altern Med Rev. 2006;11(2):93-101. Available at

  3. Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol. 1980;60(1):85-87.

  4. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection: Treatment and 
prophylaxis. Arch Dermatol. 1984;120(1):48-51.

  5. Jezova D, Makatsori A, Smriga M, et al. Subchronic 
treatment with amino acid mixture of L-lysine and L-arginine modifies neuroendocrine activation during 
psychosocial stress in subjects with high trait anxiety. 
Nutr Neurosci. 2005;8(3):155-160. 

  6. Smriga M, Ghosh S, Mouneimne Y, et al. Lysine 
fortification reduces anxiety and lessens stress in family members in economically weak communities in 
Northwest Syria. Proc Natl Acad Sci U S A. 2004;101(22):8285-8288. Available at

  7. Protein and amino acids. In: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D.C.: The National Academies Press; 2005:680. 

  8. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr. 1997;16(1):7-21.

All electronic documents accessed March 2, 2015.