Lysine and Herpes: What the Evidence Says

When you’re dealing with herpes outbreaks, it’s natural to look for something you can do yourself. Lysine is one of the most talked-about options, in supplement aisles and online. This page sets out what the best available evidence shows, what the main public health guidance recommends instead, and what it doesn’t say.

Does lysine help with herpes?

There is no good evidence that it does. Lysine is an amino acid that is sold as a supplement, and people often ask whether it helps with cold sores. When researchers pool the trials, the picture is not encouraging.

A Cochrane systematic review, indexed in PubMed by the US National Library of Medicine, looked at ways to prevent cold sores on the lips. It covered 32 randomised controlled trials with 2,640 people and 19 treatments. Its authors report that they “failed to find any evidence of efficacy for lysine” in preventing cold sores.

Some points to keep in mind:

• The review was published in 2015, and it looked at preventing cold sores in people with healthy immune systems. It did not study lysine for genital herpes.
• It rated the overall quality of evidence as low to moderate for most outcomes, so “no evidence of benefit” is not the same as proof that it could never help. It does mean there is nothing solid to recommend it on.
• The same review found that long-term use of oral antiviral medicine can prevent cold sores, although the benefit is small.

The NHS and MedlinePlus pages on cold sores don’t list lysine among the things that help. The NHS points to creams that ease pain and irritation, antiviral creams, cold sore patches, and pain relief. CDC and WHO herpes guidance doesn’t mention lysine either.

What does work for herpes?

The CDC guidance describes antiviral medicine as the mainstay of management. A clinician can prescribe it to:

• Shorten or ease a first or recurrent outbreak. CDC notes that episodic treatment shortens the duration of recurrent episodes.
• Reduce how often outbreaks happen, when taken daily as prescribed. CDC notes that suppressive therapy reduces recurrences.
• Lower the chance of passing herpes to a partner. CDC notes that daily valacyclovir reduced HSV-2 transmission in discordant couples.

The WHO lists acyclovir, famciclovir and valacyclovir as commonly used antivirals. CDC notes that episodic treatment is most effective when started within one day of the lesion appearing, or during the tingling that comes before some outbreaks. That is why it helps to have a plan agreed with a clinician in advance.

The right choice depends on you, so it is something to work out with a clinician.

What tends to trigger outbreaks?

The WHO notes that herpes simplex virus alternates between being inactive and active, and that certain triggers can reactivate it. These include illness or fever, sun exposure, the menstrual period, injury, emotional stress and surgery. For people whose oral herpes is triggered by sunlight, avoiding sun exposure and wearing sunscreen can lower the risk of recurrences.

Can any treatment cure herpes?

No. The WHO states that herpes is treatable but not curable. Medicines can reduce how long symptoms last and how severe they are, but they can’t cure the infection.

Are there risks with supplements?

Supplements are not the same as prescribed medicines, and their use with other medicines is a question for a clinician or pharmacist. Anyone with kidney or liver disease, who is pregnant or breastfeeding, or who takes other medicines should speak to a clinician or pharmacist before starting a supplement.

What should I do next?

• If you aren’t sure the sore is herpes, get it swabbed first. Other conditions can look similar.
• If outbreaks are bothering you, ask a clinician about antiviral options.
• If you still want to try lysine, ask a clinician or pharmacist first, and be wary of products that promise a cure, because no treatment cures herpes.

Supplements are a personal choice. The most important thing is that they don’t replace treatment that is known to work.