Fact Checked

How do I Use Lysine for Cold Sores?

M.J. Casey
M.J. Casey

Lysine for cold sores is a known and effective treatment for many who suffer from open sores on the lips and genitals caused by the herpes simplex virus (HSV). L-lysine, the biologically active form, is available in pharmacies, grocery stores, or specialty vitamin retailers in capsules from 500 to 1,000 mg. Excess lysine is excreted through urine, so it does not accumulate in the body. Effective dosages range from 1,000 mg up to 3,000 mg per day during an active outbreak. Lysine should not be taken with food.

HSV is acquired through contact with carriers of the virus by the exchange of body fluids such as may occur during kissing, coughing, unprotected sex, or touching open cuts. HSV is very common. Many asymptomatic people are carriers and spread the virus unknowingly. Upon infection, people will harbor the virus for the rest of their lives. The virus will lie dormant between outbreaks, at which time the carrier will become contagious.

A cold sore.
A cold sore.

Lysine for cold sores has been observed to dramatically decrease the frequency of outbreaks. Outbreaks are often triggered by some form of stress. Stress can take the form of ultraviolet light, colds, or other infections, or the anxieties of daily activities. Lysine deficiency is rare, since it is found in many proteins. Vegans using grain as their sole source of protein may need to take lysine supplements.

The structure of lysine.
The structure of lysine.

The effective dosage of lysine for treating cold sores varies from person to person. If a person has a high intake of lysine in his or her normal diet or takes B vitamins, dosages as high as three 1,000-mg capsules per day may be necessary during an outbreak. If the presence of herpes sores is a serious, frequent occurrence, 500 mg per day may be taken in between episodes. If daily vitamins are not taken, a single 1,000-mg capsule may be sufficient during outbreaks.

The right lysine dosage for cold sores depends on the individual.
The right lysine dosage for cold sores depends on the individual.

It is very important that lysine be administered immediately upon the first symptoms of cold sores. These symptoms may include a swelling, tingling, buzzing sensation, or pain in the HSV susceptible area. The treatment will be much more effective if begun within minutes of any of these symptoms. A second dose should be administered within a few hours of the first. If lysine for cold sores is used consistently, HSV outbreak’s frequency and duration are often decreased and may even disappear.

Arginine and lysine are two of the 20 essential amino acids. Proteins are often high in one of these and low in the other. HSV has been found to thrive in high-arginine environments. This suggests the lysine environment is not conducive to HSV replication. The determination of the exact mechanism of lysine for cold sores treatment is under study by multiple pharmaceutical companies.

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Discussion Comments


@SarahGen-- If you get cold sores back to back, I think you can take lysine as a cold sore medication for a longer period of time. Just don't take more than the daily recommended dose. I'm not a doctor though, so you should ask your doctor for proper advice. I take 1000mg/day when I get a cold sore and I keep taking it until it's completely gone. I also take a multivitamin with vitamin C on a regular basis to keep my immune system strong. The immune system has a lot to do with cold sores.


@SarahGen-- Lysine is a great cold sore remedy. I take my lysine supplements when I feel tingling on my lips. It prevents the cold sore from occurring if I take lysine immediately. Even if you take lysine after the cold sore has popped up, it will speed up healing and the cold sure will not become an ulcer. So even if you notice the cold sore late, you can take your lysine supplement.

There are also lysine creams at the pharmacy. You can use that too if you don't want to take the supplement. Or you could use both for a faster treatment.

People with herpes blisters may take lysine or other antivirals all the time. But I don't think people take them all the time for cold sores.


I only get cold sores during winter but they occur frequently. Should I take l-lysine supplements for cold sores throughout winter to prevent them? Are the supplements really effective when they're taken after a cold sore starts developing?

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    • A cold sore.
      A cold sore.
    • The structure of lysine.
      By: Bioreg images
      The structure of lysine.
    • The right lysine dosage for cold sores depends on the individual.
      By: Steve Silver Smith
      The right lysine dosage for cold sores depends on the individual.