Table of ContentsView AllTable of ContentsWhat Is Lysine?How Much to Take for a Cold SoreHow Does Lysine Work?Why Do I Need It?What Foods are Rich in Lysine?Special ConsiderationsFrequently Asked Questions

Table of ContentsView All

View All

Table of Contents

What Is Lysine?

How Much to Take for a Cold Sore

How Does Lysine Work?

Why Do I Need It?

What Foods are Rich in Lysine?

Special Considerations

Frequently Asked Questions

Supplemental lysine has been used to prevent and treatcold sores.

Cold sores, also known as fever blisters, are painful blisters on the side of the lips that can open and leak fluid.

The herpes simplex virus causescold sores. Theherpes virusspreads through contact with fluid in open cold sores.

This article reviews research on lysine for cold sores and any safety considerations associated with lysine supplements.

Lysine is anamino acidnecessary for human growth, health, and functioning.

Lysine is vital for making protein in the body. It also helps formcollagenand supports adequate calcium absorption.

As an essential amino acid, the body cannot produce lysine. Instead, lysine must come from food.

How Much Lysine to Take for a Cold Sore

Most people have theherpes virus, but not everyone will get a cold sore. However, once you get a cold sore, you’ll likely continue getting them.

Additional research is required to determine precisely how much lysine to take for a cold sore.

However, current research suggests dosages ranging from 500–3,000 milligrams (mg) daily, with a general recommendation of 1,000 mg daily to prevent and reduce the likelihood of future cold sores (prophylactic measures).

Higher doses of up to 3000 mg per day may be warranted for a limited time during cold sore outbreaks.

Lysine supports collagen andantibodyproduction, helping to repair tissues and fight infection.

Whetherlysine works on cold soresis still unclear.

Some research supports the benefit of lysine in reducing the healing time, number, and severity of cold sores.

Older research supportslysinefor cold sores. Supplemental lysine of 1,000 mg (1 gram) taken three times daily for six months reduced the number of cold sore infections, symptom severity, and healing time.

Conversely, other research has found no benefit of lysine for cold sores. One small study found no difference in the recurrence ofcold soresbetween participants given lysine supplements or those taking a placebo. Participants took 1,000 mg of lysine daily for six months.

However, despite limited evidence supporting its effectiveness, lysine is still commonly used to prevent and treat cold sores.

For most people, taking 1,000 mg daily of lysine is relatively harmless.

Closeup of a Black woman standing in her bathroom holding a vitamin and a glass of water.Goodboy Picture Company / Getty Images

Closeup of a Black woman standing in her bathroom holding a vitamin and a glass of water

Goodboy Picture Company / Getty Images

Why Do I Need Lysine?

Amino acids and proteins are required for countless bodily functions, including but not limited to the following:

Lysine is considered an “essential amino acid.” That means you need to get it through the food you eat.

Regardless of overall protein consumption, adequate lysine is necessary for growth and protein balance (also called nitrogen balance).

The Recommended Dietary Allowance (RDA) for lysine varies throughout the life cycle.

The RDA for people 19 and older is 38 milligrams per kilogram (mg/kg per day) or 0.017 grams per pound of body weight per day.As a reference, a person weighing 135 pounds would need 2.33 grams of lysine daily to meet the RDA.

However, the average intake of lysine from food is likely 4 to 5 grams (g) per day for adults with adequate diets.

Protein needs, in general, are higher during pregnancy.

Similarly, lysine requirements increase during pregnancy. The RDA for lysine during pregnancy is 51 mg/kg daily.

Lysine must remain elevated while breastfeeding, with your RDA at 52 mg/kg daily.

Animal-based foods tend to be high in lysine. However, it is possible to meet the recommended lysine amounts on a plant-based diet. Other foods common in a plant-based diet, like beans, are a potent source of lysine.

Foods rich in lysine include but aren’t limited to the following:

Lysine is the first limiting amino acid in cereal and grain products. Limiting amino acid refers to the protein found in the smallest amount in a food. Grain- and cereal-dominant diets may contain inadequate amounts of lysine.

Special Considerations for Lysine

For most people, lysine may be relatively harmless. However, there are some instances when lysine supplements may not be safe or effective.

Lysine Precautions

Exercise caution when taking lysine supplements if you have any of the following conditions:

Lysine Side Effects

Side effects are related to gastrointestinal issues. Reported side effects include diarrhea, nausea, vomiting, and abdominal pain.

Higher dosages (above 7,500 milligrams daily) are more likely to cause stomach issues, such as diarrhea.

Some severe side effects have been reported, including kidney (renal) dysfunction and failure.

Lysine Interactions

It is not advised to take calcium and lysine supplements concurrently, especially in people with heart disease. Lysine increases calcium absorption while decreasing excretion.This means it causes more calcium to stay in your body for longer.

Arginine (another amino acid) and lysine compete for absorption in the intestines. Consuming significant quantities of lysine (with supplements) can prevent arginine from being absorbed into the body.

When to see a healthcare providerIf you get cold sores, reach out to your healthcare provider about options to reduce pain and duration. Consider talking to your healthcare provider about lysine supplementation and whether it may be a safe and effective treatment for you.

When to see a healthcare provider

If you get cold sores, reach out to your healthcare provider about options to reduce pain and duration. Consider talking to your healthcare provider about lysine supplementation and whether it may be a safe and effective treatment for you.

Summary

Lysine is an essential amino acid. Although some research suggests lysine may prevent or reduce the severity of cold sores, data is limited.

If you are prone to cold sores, supplementing regularly with 1,000 mg of lysine may reduce their occurrence. However, limited research is available on taking lysine for cold sores.

Talk with your healthcare provider to see if lysine will be safe and effective for you.

Based on the available research, supplementing with 1,000 mg daily of lysine may prevent cold sores. Upping the dosage of lysine to 3,000 mg at the onset of a cold sore may reduce its severity and duration.

Older research shows supplementing with lysine shortens the duration of a cold sore. Cold sores can last up to 21 days. However, two studies noticed that lysine healed cold sores within six days.Still, additional and more recent research is needed.

26 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Institute for Quality and Efficiency in Health Care (IQWiG).Cold sores: overview.PubChem.Lysine (Compound).Matthews DE. (2020).Review of lysine metabolism with a focus on humans.The Journal of nutrition,150(Suppl 1), 2548S–2555S. doi.org/10.1093/jn/nxaa224Pedrazini MC, da Silva MH, Groppo FC.L-lysine: Its antagonism with L-arginine in controlling viral infection. Narrative literature review.Br J Clin Pharmacol. 2022;88(11):4708-4723. doi:10.1111/bcp.15444Mailoo VJ, Rampes S.Lysine for herpes simplex prophylaxis: a review of the evidence.Integr Med (Encinitas). 2017;16(3):42-46.Griffith RS, Walsh DE, Myrmel KH, et al.Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis.Dermatologica. 1987;175(4):183-190.Chi CC, Wang SH, Delamere FM, et al.Interventions for prevention of herpes simplex labialis (cold sores on the lips).Cochrane Database Syst Rev. 2015;2015(8):CD010095. doi:10.1002/14651858.CD010095.pub2Hayamizu K, Oshima I, Nakano M.Comprehensive safety assessment of L-lysine supplementation from clinical studies: A systematic review.J Nutr. 2020;150(Suppl 1):2561S-2569S. doi:10.1093/jn/nxaa218Lopez MJ, Mohiuddin SS.Biochemistry, essential amino acids. StatPearls Publishing; 2023.Institute of Medicine.Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. The National Academies Press. 2005. https://doi.org/10.17226/10490.Hayamizu K, Oshima I, Fukuda Z, et al.Safety assessment of L-lysine oral intake: A systematic review.Amino Acids. 2019;51(4):647-659. doi:10.1007/s00726-019-02697-3MyFoodData.Nutrition facts search tool: lean chicken breast (cooked).FoodData Central.Fish, haddock, raw.MyFoodData.Total amino acid protein calculator: shrimp.FoodData Central.Pork, fresh, loin, tenderloin, separable lean and fat, raw.FoodData Central.Beef, ground, 80% lean meat/20% fat, raw.FoodData Central.Soybeans, mature seeds, raw.FoodData Central.Nuts, pistachio nuts, raw.FoodData Central.Seeds, chia seeds, dried.FoodData Central.Fish, sunfish, pumpkin seed, raw.FoodData Central.Egg, whole, raw, fresh.FoodData Central.Beans, black, mature seeds, raw.FoodData Central.Lentils, pink or red, raw.MedlinePlus.Lysinuric protein intolerance.Walsh DE, Griffith RS, Behforooz A.Subjective response to lysine in the therapy of herpes simplex.J Antimicrob Chemother. 1983;12(5):489-496. doi:10.1093/jac/12.5.489Singh BB, Udani J, Vinjamury SP, et al.Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes.Altern Med Rev. 2005;10(2):123-127.

26 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Institute for Quality and Efficiency in Health Care (IQWiG).Cold sores: overview.PubChem.Lysine (Compound).Matthews DE. (2020).Review of lysine metabolism with a focus on humans.The Journal of nutrition,150(Suppl 1), 2548S–2555S. doi.org/10.1093/jn/nxaa224Pedrazini MC, da Silva MH, Groppo FC.L-lysine: Its antagonism with L-arginine in controlling viral infection. Narrative literature review.Br J Clin Pharmacol. 2022;88(11):4708-4723. doi:10.1111/bcp.15444Mailoo VJ, Rampes S.Lysine for herpes simplex prophylaxis: a review of the evidence.Integr Med (Encinitas). 2017;16(3):42-46.Griffith RS, Walsh DE, Myrmel KH, et al.Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis.Dermatologica. 1987;175(4):183-190.Chi CC, Wang SH, Delamere FM, et al.Interventions for prevention of herpes simplex labialis (cold sores on the lips).Cochrane Database Syst Rev. 2015;2015(8):CD010095. doi:10.1002/14651858.CD010095.pub2Hayamizu K, Oshima I, Nakano M.Comprehensive safety assessment of L-lysine supplementation from clinical studies: A systematic review.J Nutr. 2020;150(Suppl 1):2561S-2569S. doi:10.1093/jn/nxaa218Lopez MJ, Mohiuddin SS.Biochemistry, essential amino acids. StatPearls Publishing; 2023.Institute of Medicine.Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. The National Academies Press. 2005. https://doi.org/10.17226/10490.Hayamizu K, Oshima I, Fukuda Z, et al.Safety assessment of L-lysine oral intake: A systematic review.Amino Acids. 2019;51(4):647-659. doi:10.1007/s00726-019-02697-3MyFoodData.Nutrition facts search tool: lean chicken breast (cooked).FoodData Central.Fish, haddock, raw.MyFoodData.Total amino acid protein calculator: shrimp.FoodData Central.Pork, fresh, loin, tenderloin, separable lean and fat, raw.FoodData Central.Beef, ground, 80% lean meat/20% fat, raw.FoodData Central.Soybeans, mature seeds, raw.FoodData Central.Nuts, pistachio nuts, raw.FoodData Central.Seeds, chia seeds, dried.FoodData Central.Fish, sunfish, pumpkin seed, raw.FoodData Central.Egg, whole, raw, fresh.FoodData Central.Beans, black, mature seeds, raw.FoodData Central.Lentils, pink or red, raw.MedlinePlus.Lysinuric protein intolerance.Walsh DE, Griffith RS, Behforooz A.Subjective response to lysine in the therapy of herpes simplex.J Antimicrob Chemother. 1983;12(5):489-496. doi:10.1093/jac/12.5.489Singh BB, Udani J, Vinjamury SP, et al.Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes.Altern Med Rev. 2005;10(2):123-127.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Institute for Quality and Efficiency in Health Care (IQWiG).Cold sores: overview.PubChem.Lysine (Compound).Matthews DE. (2020).Review of lysine metabolism with a focus on humans.The Journal of nutrition,150(Suppl 1), 2548S–2555S. doi.org/10.1093/jn/nxaa224Pedrazini MC, da Silva MH, Groppo FC.L-lysine: Its antagonism with L-arginine in controlling viral infection. Narrative literature review.Br J Clin Pharmacol. 2022;88(11):4708-4723. doi:10.1111/bcp.15444Mailoo VJ, Rampes S.Lysine for herpes simplex prophylaxis: a review of the evidence.Integr Med (Encinitas). 2017;16(3):42-46.Griffith RS, Walsh DE, Myrmel KH, et al.Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis.Dermatologica. 1987;175(4):183-190.Chi CC, Wang SH, Delamere FM, et al.Interventions for prevention of herpes simplex labialis (cold sores on the lips).Cochrane Database Syst Rev. 2015;2015(8):CD010095. doi:10.1002/14651858.CD010095.pub2Hayamizu K, Oshima I, Nakano M.Comprehensive safety assessment of L-lysine supplementation from clinical studies: A systematic review.J Nutr. 2020;150(Suppl 1):2561S-2569S. doi:10.1093/jn/nxaa218Lopez MJ, Mohiuddin SS.Biochemistry, essential amino acids. StatPearls Publishing; 2023.Institute of Medicine.Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. The National Academies Press. 2005. https://doi.org/10.17226/10490.Hayamizu K, Oshima I, Fukuda Z, et al.Safety assessment of L-lysine oral intake: A systematic review.Amino Acids. 2019;51(4):647-659. doi:10.1007/s00726-019-02697-3MyFoodData.Nutrition facts search tool: lean chicken breast (cooked).FoodData Central.Fish, haddock, raw.MyFoodData.Total amino acid protein calculator: shrimp.FoodData Central.Pork, fresh, loin, tenderloin, separable lean and fat, raw.FoodData Central.Beef, ground, 80% lean meat/20% fat, raw.FoodData Central.Soybeans, mature seeds, raw.FoodData Central.Nuts, pistachio nuts, raw.FoodData Central.Seeds, chia seeds, dried.FoodData Central.Fish, sunfish, pumpkin seed, raw.FoodData Central.Egg, whole, raw, fresh.FoodData Central.Beans, black, mature seeds, raw.FoodData Central.Lentils, pink or red, raw.MedlinePlus.Lysinuric protein intolerance.Walsh DE, Griffith RS, Behforooz A.Subjective response to lysine in the therapy of herpes simplex.J Antimicrob Chemother. 1983;12(5):489-496. doi:10.1093/jac/12.5.489Singh BB, Udani J, Vinjamury SP, et al.Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes.Altern Med Rev. 2005;10(2):123-127.

Institute for Quality and Efficiency in Health Care (IQWiG).Cold sores: overview.

PubChem.Lysine (Compound).

Matthews DE. (2020).Review of lysine metabolism with a focus on humans.The Journal of nutrition,150(Suppl 1), 2548S–2555S. doi.org/10.1093/jn/nxaa224

Pedrazini MC, da Silva MH, Groppo FC.L-lysine: Its antagonism with L-arginine in controlling viral infection. Narrative literature review.Br J Clin Pharmacol. 2022;88(11):4708-4723. doi:10.1111/bcp.15444

Mailoo VJ, Rampes S.Lysine for herpes simplex prophylaxis: a review of the evidence.Integr Med (Encinitas). 2017;16(3):42-46.

Griffith RS, Walsh DE, Myrmel KH, et al.Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis.Dermatologica. 1987;175(4):183-190.

Chi CC, Wang SH, Delamere FM, et al.Interventions for prevention of herpes simplex labialis (cold sores on the lips).Cochrane Database Syst Rev. 2015;2015(8):CD010095. doi:10.1002/14651858.CD010095.pub2

Hayamizu K, Oshima I, Nakano M.Comprehensive safety assessment of L-lysine supplementation from clinical studies: A systematic review.J Nutr. 2020;150(Suppl 1):2561S-2569S. doi:10.1093/jn/nxaa218

Lopez MJ, Mohiuddin SS.Biochemistry, essential amino acids. StatPearls Publishing; 2023.

Institute of Medicine.Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. The National Academies Press. 2005. https://doi.org/10.17226/10490.

Hayamizu K, Oshima I, Fukuda Z, et al.Safety assessment of L-lysine oral intake: A systematic review.Amino Acids. 2019;51(4):647-659. doi:10.1007/s00726-019-02697-3

MyFoodData.Nutrition facts search tool: lean chicken breast (cooked).

FoodData Central.Fish, haddock, raw.

MyFoodData.Total amino acid protein calculator: shrimp.

FoodData Central.Pork, fresh, loin, tenderloin, separable lean and fat, raw.

FoodData Central.Beef, ground, 80% lean meat/20% fat, raw.

FoodData Central.Soybeans, mature seeds, raw.

FoodData Central.Nuts, pistachio nuts, raw.

FoodData Central.Seeds, chia seeds, dried.

FoodData Central.Fish, sunfish, pumpkin seed, raw.

FoodData Central.Egg, whole, raw, fresh.

FoodData Central.Beans, black, mature seeds, raw.

FoodData Central.Lentils, pink or red, raw.

MedlinePlus.Lysinuric protein intolerance.

Walsh DE, Griffith RS, Behforooz A.Subjective response to lysine in the therapy of herpes simplex.J Antimicrob Chemother. 1983;12(5):489-496. doi:10.1093/jac/12.5.489

Singh BB, Udani J, Vinjamury SP, et al.Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes.Altern Med Rev. 2005;10(2):123-127.

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