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What is Lysine?

Niki Acker
Updated Mar 03, 2024
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Lysine is an amino acid found in nature, and which the human body has to get from food sources. As a building block of protein, it serves a number of different functions, and although deficiency is relatively uncommon, low levels can cause health problems. People sometimes use it in supplement form to control outbreaks of the herpes virus, and research is being done in other areas of application, such as osteoporosis treatment. Some side effects have been reported, mainly when doses are high.

Chemical Properties

This compound is known chemically through the formula C6H14N2O2 and has a molar mass of 146.19. It is soluble in water and is polar, having a positive charge. Scientists consider it to be one of three basic amino acids — the other two being arginine and histidine — which means it has basic side chains at a neutral pH.


In living organisms, including people, this substance has several roles, the main one of which is to serve as a building block for protein. The body also uses it to construct collagen, hormones, enzymes and antibodies, which are necessary for a wide range of physical processes and good overall health. Studies show that it also boosts calcium absorption while reducing the amount excreted in the urine, and that it can affect both energy and cholesterol levels through the production of carnitine. This substance also influences the amount of nitrogen in the body.


People cannot produce lysine on their own, meaning they have to get it through what they eat. Good sources include red meats, pork, poultry, cheese and eggs, but many plants also provide it, particularly legumes such as beans. Nuts are another common way to bring it into the diet. Vegetarians are able to combine plants that have it in high levels with grain products to ensure they get the right proportions of all essential amino acids, so it isn’t necessary to rely on animals or animal products to get enough.

The way someone prepares a meal can make a big difference in how much of the amino acid he actually gets. Cooking, for example, often reduces this substance’s bioavailability, which is the amount of a chemical the body is able to absorb. In many cases, it is best to eat the food raw, but other risks sometimes outweigh the benefits of doing this, such as getting a bacteria-borne illness from raw meat.

Signs of Deficiency

In some rare cases where someone doesn’t consume enough of the compound, or when a medical issue interferes with how the body processes it, signs of low levels can appear. These are numerous, because so many physical processes rely on the availability of protein. Some of the more common symptoms, however, include anemia, weight loss or a reduction in lean muscle mass, poor recovery from injuries and tiredness. Changes in appetite and mood frequently occur because of the relationship of lysine to hormone production.

Herpes Treatment

As a medication, lysine is used probably most commonly in the treatment of herpes simplex labialis, better known simply as herpes or cold sores. It works best as a preventative option, although it can reduce how long an outbreak lasts. Medical professionals believe it works for this purpose because it blocks arginine, a substance that makes it easier for the herpes virus to reproduce. They recommend high doses of 1,000 milligrams or more for this use, as well as keeping foods high in arginine limited.


Due to its ability to affect calcium levels, this amino acid might have big potential as a treatment for osteoporosis, which is a condition in which the amount of minerals and protein in the bones goes down, making them brittle, porous and easier to break. This is largely a theory based on what medical professionals know about how lysine works, however. Research studies have yet to confirm whether supplements could slow or alleviate symptoms of the disease.

Other Uses

Some individuals try to improve the amount of lysine in their diets or take supplements as a way to encourage growth and prevent muscle loss. Weightlifters and other athletes, for example, are careful to watch their intake, and researchers are looking into how it might help people with conditions related to muscle deterioration. Studies also have investigated possible uses for mood disorders, particularly anxiety, blood sugar regulation and pain control, but more investigation is needed before experts can say their results are verifiable and reproducible. Outside of the medical industry, farmers routinely add it to animal feed — this practice has been common already for several decades.


For a typical adult, the recommended daily dose of lysine is 12 milligrams per kilogram of body weight, which, on average, works out to about 840 milligrams. Some individuals need as much as 3,000 milligrams, however. Although children need and can take it, caregivers and medical professionals need to adjust the administered amount based on weight and age.

Side Effects

High doses, such as those used in herpes treatment, should be approached with some caution, because they have been linked to kidney problems and gall stones. Anyone who already has these issues should not take supplements. Some individuals also have experienced issues with diarrhea and abdominal discomfort, which might be because of lysine’s connection to serotonin production, which influences digestion. Nausea can occur with these gastrointestinal symptoms.


In supplement form, lysine is available as capsules, tablets and liquids, making oral administration simple. People also put it in topical creams and lotions, typically in combination with many other ingredients. Which version is appropriate depends on why an individual wants or needs to supplement. Treatment of skin conditions such as burns, for example, might be more effective with topical types, while an athlete or vegetarian might prefer an oral version.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
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Niki Acker
By Niki Acker
"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range of interesting and unusual topics to gather ideas for her own articles. A graduate of UCLA with a double major in Linguistics and Anthropology, Niki's diverse academic background and curiosity make her well-suited to create engaging content for WiseGeekreaders. "
Discussion Comments
By anon935039 — On Feb 23, 2014

I was diagnosed with genital herpes three days ago. I feel devastated. I have an OB very bad and I am taking Acyclovir. I know it might take a week or more to get better, but I would like to start a diet and I've been reading about lysine. Do I need prescription to buy Lysine, or is it an over the counter medicine?

By anon327257 — On Mar 27, 2013

I suggest looking up a high lysine, low arginine food list. That is what I did and it gives you the amount of each that each food has so you can make smart decisions while grocery shopping.

By anon316777 — On Jan 30, 2013

I had taken the lysine for about a couple of weeks and did not see any fever blisters for a whole year, and thank God. I have had them since I was five years old and mom said a man kissed me and he had a fever blister and gave me herpes, but a different kind since I don't have the breakouts only on my lips and that has almost gone since I also have been taking flax oil pills. They're only $5 for 90 at Wal-mart and what a difference. I've hardly had any breakouts.

By anon286295 — On Aug 20, 2012

@googlefanz: Per my naturopath's directions, I take 500mg twice daily for prevention, and 1000mg three times daily if I get an OB. Most important for me is reducing bodily stress, especially by getting enough sleep regularly, but also eating healthy and exercising. That's gotten me off Acyclovir.

By anon197302 — On Jul 16, 2011

I found out that I had genital herpes around a year ago. I was distraught! However, I found out about lysine. I tried it and it has so far worked. I say this because i was having outbreaks every three months and 'doomsday' has been and gone with no bother at all. Fingers crossed.

By smn30 — On Feb 27, 2011

I had outbreaks every month or less. Then I started to pay attention to my diet. I stopped all kinds of nuts and chocolate. Used more dairy products and took one 1000mg L.Lysine daily. After that, thank God, I have not have a breakout yet.

While my doctor does not believe that L.Lysine works for herpes. But it seems to be working for me.

By googlefanz — On Aug 30, 2010

Has anybody out there actually taken lysine for genital herpes? My partner has herpes simplex, and the doctor said that taking lysine might help.

However, I was looking it up, and apparently lysine has a lot of side effects. So my question is, is herpes simplex affected by lysine, and if so, what is a good daily lysine dose?

We want to get the highest dose that we can without getting the side effects.

Any advice?

By StreamFinder — On Aug 30, 2010

@Charlie89 -- Well, as the article said, your best best are legumes, fish, and dairy products.

If you want to take lysine specifically for cold sores or herpes, then you not only need to get foods rich in lysine, but low in arginine as well.

So be sure to stock up on the cheeses, fish, milk and grain, but skip your crustaceans and nuts.

The best foods for lysine, of course, are those which combine some of the above foods. For instance, a salmon/cheese bake, or tofu mixed with noodles or grains.

Anyway, best of luck -- experiment around with those kinds of food, and you should be good to go.

By Charlie89 — On Aug 30, 2010

What are some good lysine foods? I don't want to take the pure lysine supplements, but I still want to get all the good lysine benefits.

Any tips?

By anon12869 — On May 15, 2008

My cat was born with one eye shut. I got her ointment, cleaned it, etc. She's been cross-eyed now for 6 1/2 years-along with wet, goopy eye & sneezing. My brother was here to visit 2 weeks ago and said his cat was "google-eyed", too, until he started giving her Lysine-1 tab daily. I tried it on my cat. It's only been 2 weeks and she's no longer crossed-eyed!!!!!!!!!!!!

Niki Acker
Niki Acker
"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range...
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