cold sores

Cold sores are painful. They are also unsightly. Perhaps more alarming, there is some research to suggest that cold sores may increase the risk for Alzheimer’s disease (see this link). Could L-lysine for cold sores protect the brain from dementia? See this link for a response to that question. A reader wants to know that the science is behind L-lysine against cold sores.

Q. I’ve had cold sores since I was young. I have spoken with doctors about them innumerable times.

In your column, you often recommend taking L-lysine. This product has not shown efficacy in peer-reviewed clinical trials, as far as I’ve heard. It is just one of the home-remedy folk “cures” that show up in your columns. Even acyclovir and valacyclovir are of limited efficacy.

A. Cold sores are caused by herpes simplex virus type 1. It hides out in the body and appears in the form of a cold sore lesion on the lips or face in the event of a drop in immunity, exposure to intense sunlight or increased stress (BMJ Clinical Evidence, online Sep. 23, 2009).

A comprehensive Cochrane review supports your stance on L-lysine against cold sores (Cochrane Database of Systematic Reviews, Aug. 7, 2015).  That could be due to a lack of studies rather than a lack of efficacy, however. Long-term use of the antiviral drugs acyclovir or valacyclovir was modestly effective in preventing cold sores.

Stories About L-lysine Against Cold Sores:

Despite such negative news, we continue to hear from readers that L-lysine works for many people. Here are just a few testimonials:

“Lysine tablets work for me. At the first tingle of a beginning cold sore, I take a 500 mg tablet. Then I take another 500 mg tablet later on that day.
“I try to take 1000 mg a day for several days. By then, there is either a small cold sore that goes away early or else no cold sore at all. Usually it’s the latter.”

Gael brings her biochemistry background to bear:

“I find L-lysine against cold sores to be very effective. I read recently that prevention is best, so I now take a 1,000 mg tablet each morning with breakfast.

“Having studied biochemistry long ago, I hypothesize that the herpes virus needs arginine to build its protein coat. Lysine is similar in structure to arginine; perhaps when there is more lysine than arginine, it inhibits the virus’s ability to replicate. If I do get the beginnings of a cold sore, I increase the dose to one tablet with each meal. I also try to avoid foods high in arginine, such as nuts and chocolate, when I have a cold sore.”

Nat has an interesting regimen to share:

“I used to get cold sores at least once every 2 months. And when I would have an outbreak, there would not be just one, but a whole CLUSTER of them in the same spot. So embarrassing and painful.

“I heard of L-Lysine and have been taking it. I don’t take it every day. As and when needed.

“If I look closely in the mirror and see a slight color change or texture change on my lips I take a 500mg tablet before bed or whenever I noticed it.

“When I feel like one is coming on I would up the dose to 1000 mg. DOES THE TRICK!

“I am not joking. Two days ago I woke up with the tell-tale bubble on the lip. I put ice in a sandwich bag and held the ice on my lip for 3 minutes (it kills the pain; feels like frostbite but helps to reduce the newly forming cold sore under the skin). Then I doused it with acyclovir antiviral cream. (I put a thin layer on if I am going to work; otherwise it’s embarrassing).

“Then as SOON as I saw it, I took 1000mg L-lysine. I find the cold sore diminished throughout the day. After work I slathered on cream and went to bed and the next morning. GONE!”

Share your own experience with L-lysine against cold sores in the comment section below.

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  1. susan
    orlando fl

    I had the herpes virus for 40 some years. Before any knowledge, I would break out from my lips through the whole side of my face. I started taking Valacyclovir at first start of an outbreak for 2-3 days and it stayed as a mild attack and went away quickly. I used L-lysine and it helped but not as much. Then I turned 60 and got a shingles virus shot about 3 years ago and have not had any breakout at all since then.

  2. Nancy

    Years ago, I was getting cold sore after cold sore after cold sore. Then I read about trigger foods and realized that the cashews that I was liberally enjoying were one big source of the problem. Then I learned about L-lysine, which I began taking daily. Then I heard that it isn’t good to take it all the time, that it upsets the balance of amino acids. So I now go easy on the trigger foods and just take some L-lysine if I feel one coming, or if I eat some chocolate or extra nuts. This seems to work for me.

  3. Joyce

    I have taken L-Lysine twice a day for years. My observation was stress brought them on. Knowing I get cold sores I wanted to avoid passing them to my husband. Works for me.

  4. Shari
    Palm City, FL

    Last year I had 8 cold sores in 6 months. Valacyclovir helped shorten the healing process, but I was still dealing with the sores every month. Then I read your column. I decided to try L-lysine, despite the skeptical reaction of my doctors. I take one tablet every other day. I have had only one cold sore for all of 2017! And the duration of that single sore was shortened considerably! I am amazed and grateful. Thank you!

    • Rick

      Cold sores are activated very similar to herpes as both are brought on by stress. That would mean that your cortisol levels the stress hormone is fatigued for a better word. Yes adrenal fatigue is one of the major health problems through out the world. The reason it is not recognized as a syndrome is simple medications are one of the major contributors to cortisol depletion. Practically every synthetically produced medication triggers an immune response and by doing so causes body stressors

  5. Lorraine

    L-Lysine has kept me canker and cold sore free. I suffered with them often during childhood and beyond all my life until I found L-Lysine. I haven’t had a sore since, and it’s been about 20 years. I’m old! I take 500 mg in the a.m. daily and, if I feel the slightest puffiness on my lip, inside cheek, or tongue, I take more. Each time it begins to swell, I take more until the feeling is gone. I carry some meds with me, including L-Lysine, and keep some at work and home. I’ve asked pharmacists and physicians who tell me I can’t overdose, so I take no chances, 500 mg at a time. Thanks, everyone, for sharing.

    • John
      North Carolina

      You are absolutely correct!!! Same here and I am blessed that I learned of this 30 years ago!!! Anyone who says it doesn’t work is probably affiliated with Big Pharma who wants a more expensive solution with a 10th of the results of this mineral that the body does not produce!!!

  6. Eleanor

    All you have to do if you get a cold sore, or feel one coming on is
    Put perfume or shaving lotion on it a few times. [it will be gone]

  7. JJ

    I had herpes I, which is what really sores on the mouth or lips are, for 40+ years.
    I started 5 years ago applying Hemp Seed Oil daily or every two days and haven’t had an occurrence.
    I feel the tingle/itch and apply several times a day and it’s totally blocked from surfacing.
    I use a cleaned Visine/EYE Drop dispenser for application…just a drop is sufficient for blocking herpes I.
    Yes, folks, it’s herpes…kin to smallpox.


    I have had viral sores on the corners of my lips almost since infancy and I have used l-ysine now for almost 70 years! ! !
    I now put as much as a heaping teaspoon of l-lysine in my coffee and for instant relief i wet a tissue or a cotton ball with 91% alcohol and hold it on the sore or blister.
    To speed up the healing use a needle to pierce the blister and apply the alcohol again for 10 to 20 minutes .

    The ” l ” in front of the l- lysine indicates that it is the left oriented molecule otherwise it is an ‘ r ‘ for the right and the ‘ n ; for normal or natural ! ! !

    And another thing, peanuts contain an enormous amount of arginine and arginine increases the replication speed of the herpes viruses

  9. WK

    I have a long standing battle with HSV1. Eating chocolate or nuts seems to lower my immunity LLysine can abort an attack but my very wise ENT has cautioned me to not stay on it as he is concerned about its effect on the body’s ability to absorb arginine

  10. John
    Tonawanda, NY

    I have been using Lysine for years whenever a cold sore starts to develop. It works!!

    • Rick

      Yes chocolate and caffeine trigger your adrenals which can lower cortisol levels needed to protect you from stress

  11. Sarah
    North Carolina

    After having read all the previous …L-lysine emails…. I agree that it does work for some people but not for others. My ex-boyfriend, for instance, had adverse effects from L-lysine (maybe it was the brand he bought?) but I’ve taken L-lysine for over 25+years & this is what I’ve found.

    Not only do I never get colds….but I also very rarely get any of the circulating flu illnesses making the rounds. That’s because L-lysine also fights any viruses! The only time I got the flu was many years ago when my Mom convinced me to get a flu shot to avoid a very serious & supposedly dangerous flu virus that was spreading around the country.

    After getting the flu shot…I came down with a very strong case of flu within a few days. I’ve never gotten the flu since…but then I’ve also never received any more *flu vaccinations* either since then.

    So, to summarize, if L-lysine doesn’t affect you adversely… I highly recommend it for daily usage as an overall cold, flu, and coldsore preventative. It’s one of the most amazing of all the trace amino acid groups in my experience!

  12. Relieved

    I realized when I snack on large quantities of some types of nuts I get cold sores. For some reason around December I also tend to get Cold sores. I then ta ke large doses of L-Lysine 4,000 units a day and in a week or so sometimes sooner my lips are healing. When I remember to, I take a 1000maintenance dose a day and I believe this helps me avoid cold sore flare-ups. I wonder if this helps inflammation in other hidden areas of my body

  13. Diane in Western New York

    I don’t suffer from cold sores, but I had suffered from an itchy and then sore pustular skin outbreak on my feet for over 40 years. It was treated by several PC’s, dermatologists and allergy doctors without solving the problem. It occurred to me that it appeared every year between October and November and lasted until May or June, driving me crazy.

    It always came back at the same spots, and as the years went by it gradually spread. I suggested to my new PC that it might be viral. She agreed and told me that when it next appeared to go for viral blood testing right away. I did, and yes, it was a herpes simplex virus. I was put on Valtrex and it began to go away within 12 hours! I also felt better than I had in decades. Then my husband came down with Shingles in his eye.

    In researching that, I came across L-Lysine as an anti-viral when taken on an empty stomach. According to that information,if taken with food it will be used in the building of cell walls. I decided to try it. Most of the time, taking 1000mg per day first thing in the morning works to keep my virus quiet. When I am not getting enough sleep or I begin to come down with a cold or my allergies are especially bad and the skin rash appears, I take more L-Lysine until the symptoms subside. Sometimes that means as much as 9,000mg/day.

    If the L-Lysine stops the process, I continue at that level and then try to gradually back off. If the symptoms get worse, I go back to the working amount. Eventually, I am able to get back to 1000mg/day. If, despite the increased amount, the rash continues, then I take the Valtrex (which I keep on hand) for a week and that stops it. I have not had to use Valtrex since 2014. The L-lysine in various amounts has been keeping the virus in check. Most of the time it works for me. It also worked for my husband’s shingles. As soon as his eye would show a little red, he would start taking the L-lysine and it would go away. Then he would gradually back off.

  14. Elizabeth

    I have been using L Lysine for years. Once I shared my list of supplements with my Hematologist-Oncologist, he scratched the L Lysine off the list, I stopped taking it and immediately, within days had an outbreak, I started right back on the L Lysine.

    Because of some of the drugs I have been on, I currently take 500 mg Valtrex daily, so I’ve had no outbreaks in quite awhile. It was suggested to me in the first place by a friend who is a Nurse Practitioner.

  15. Nana

    I have found L-lysine to be AMAZING!! I don’t take it unless I feel a tingle, then I start taking 1000 mg three times a day. The herpes never erupts! I stop the L-lysine after a few days and don’t take it until I get another tingle.

    The tingles are few and far between, now. I swear by it and recommend it to anyone who gets herpes.

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