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Lysine For Cold Sores: Does It Work?

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Medically Reviewed By Colgate Global Scientific Communications

Cold sores, which are caused by the herpes simplex virus type 1 (HSV-1), can be uncomfortable and make you feel self-conscious. They usually develop on or near the lips but can form inside the mouth, too. According to the National Institutes of Health (NIH), more than half of all Americans will have an HSV-1 infection by their 20s, making this a common concern.

If you experience regular cold sore outbreaks, you might be wondering how to best treat your cold sores and prevent them from reoccurring. Besides prescription treatments, some people have tried lysine for cold sores, as well as other natural cold sore remedies. But is lysine worth trying, and will it really help to prevent these sores?

What Is Lysine?

Lysine is one of nine essential amino acids, which are compounds that combine to form proteins, as the NIH notes. Your body needs these to grow, repair itself and digest food. The human body doesn't produce these essential amino acids on its own, so instead, you get them from food or from taking supplements.

Lysine, in particular, also plays a role in helping your body develop collagen and absorb calcium, and it aids in the production of carnitine, which may help to lower cholesterol levels, according to PennState Hershey Milton S. Hershey Medical Center.

Meat, cheese, eggs, beans (especially soybeans) and fenugreek are all good sources of lysine. And while most people get an adequate amount of lysine from their diet, those who exercise a lot or those who follow a vegan diet and avoid beans might be lysine deficient.

Will Lysine Help Prevent Cold Sores?

Lysine is occasionally promoted as a natural remedy for cold sores. The Mayo Clinic lists it as an alternative treatment option, available as either an oral supplement or a cream, and PennState Hershey Milton S. Hershey Medical Center notes that lysine supplements may potentially help to reduce the occurrence of cold sore outbreaks, though not all experts believe it works.

One theory on why lysine is thought to help reduce cold sore outbreaks is that the amino acid may interfere with the activity of arginine, another amino acid, and block herpes replication, according to an article in Clinical Advisor.

So far, studies focusing on lysine for cold sores in humans haven't drawn any firm conclusions. One study, published in Integrative Medicine: A Clinician's Journal, revealed that lysine supplementation of less than 1 gram per day wasn't effective at treating or preventing cold sore outbreaks, but higher doses — above 3 grams per day — seemed to have a positive effect on patients. In contrast, a Cochrane review found that lysine offered no preventative effects against cold sores.

Other Cold Sore Treatment Options

While it's uncertain whether taking an oral lysine supplement or using a cream containing lysine could provide the results you may be looking for, it's worth noting that you have many other cold sore treatment options.

The Mayo Clinic assures that blisters do typically clear up on their own within two to four weeks, but if you are interested in a quicker recovery, your doctor might prescribe an oral medication, such as valacyclovir or acyclovir, to help speed up the healing process. At-home treatments, such as using a cold compress, applying lip balm or using an over-the-counter cold sore cream, can also help ease your discomfort.

Another way to cope with HSV-1 is to learn what triggers your outbreaks and try to avoid those triggers. Some people find that stress often leads to the formation of blisters, for example. Practicing stress reduction techniques, such as meditation and deep breathing, might help you relax and avoid an outbreak.

Ultimately, the best thing to do if you're curious about trying lysine for cold sores is talk to your doctor. They can give you advice on the benefits or drawbacks of using a supplement and can recommend other treatments to keep your cold sores under control.


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This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.

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