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What is Lysine Hydrochloride?

By Angela Crout-Mitchell
Updated Mar 03, 2024
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Lysine hydrochloride is one of the most often used amino acids in supplement form and has several useful properties for improving health. This acid is especially good for helping the body fully absorb calcium as well as reducing the symptoms of herpes simplex infections. It can also be taken to treat common mouth, sores such as canker sores, and other infections. In most cases, lysine can be taken as part of a daily supplemental regimen or as needed to treat herpes outbreaks or infections. There are no known adverse side effects, as this amino acid is necessary for healthy body functions and is produced by the body as well.

The most well-known use for lysine hydrochloride is as an effective treatment for the herpes simplex virus. This virus manifests with painful sores of the mouth, commonly referred to as cold sores. It is believed that lysine helps control these conditions by inhibiting the strength of another amino acid, arginine, which can contribute to the appearance of cold sores. Lysine hydrochloride works to inhibit the production of the herpes simplex virus by slowing, if not eliminating, the effects of the virus. In studies it has been suggested people taking placebos experienced twice as many herpes outbreaks as those who were given lysine supplements.

Another use for lysine is in treating common canker sores of the mouth. The cause of these small, painful sores is still unknown, but the medical opinion as of the early 2000s is that they are caused by some kind of virus. This theory reflects the already known antiviral properties of the amino acid and its effects on the herpes virus.

A less well-known use for lysine hydrochloride is relieving shingle outbreaks by adversely affecting the dormant chicken pox virus that causes the condition. This virus, Herpes zoster, is similar in composition to the herpes simplex virus and creates painful sores that often appear on the trunk of the person affected, though they can appear in other areas as well. Anyone who has been affected by chicken pox in the past can have shingles, but it is more likely to affect people with lower immune defenses, such as those with diabetes or any other kind of immune system depression. Lysine is usually used in combination with antiviral medications in this situation.

In order for lysine supplements to be effective, the substance has to be taken in the correct dosage. During a herpes simplex infection or any other acute viral infection, it recommended to take 1,000 mg three times a day for the best results. Once the sores or virus has cleared up, it is a good idea to continue with the lysine treatment at 500 mg three times a day for about one week.

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Discussion Comments
By anon949359 — On May 04, 2014

Bit off topic, but this made a huge difference for my cats with feline herpes which manifests as respiratory and eye problems. The sneezing stopped within two days of use on cats showing mild symptoms and not on antivirals at the time. I was astonished because I really didn't expect any visible results.

By SarahGen — On Feb 04, 2014

There is a lot of controversy about what l-lysine hydrochloride is beneficial for. As far as I know, there actually aren't enough studies that show that lysine is beneficial for canker sores or shingles. It has only been shown to be beneficial for herpes simplex type 1 (cold sores) and herpes simplex type 2 (genital herpes). Has anyone seen actually seen any studies showing that lysine works for canker sores or shingles?

By discographer — On Feb 04, 2014

@fBoyle-- Yes, but you should take them at the first sign of a blister, instead of taking them regularly for long periods of time. Some people do take a low dose of l-lysine tablets during winter to prevent the flu. But for cold sores, doctors recommend taking high doses of lysine at the first sign.

So when you start feeling tingling on your lip, you need to start taking the lysine right away. 1000mg/day is a good dose although I know people who take higher doses. A few days of lysine is usually enough for prevention. If it's too late and the blister has already formed, you can still take lysine during the duration of the blister to speed up healing.

But I don't think it's a good idea to take very high doses of lysine for long periods of time. Our daily requirement for lysine is very low, it's less than 20mg/day for adults. So 1000mg is a very high dose and lysine can cause side effects.

By fBoyle — On Feb 04, 2014

Can I use l-lysine HCL to prevent cold sore blisters? I only get blisters in winter, so can I take a lysine supplement during winter to prevent them?

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