How Much Lysine to Take for Cold Sores, According to a Dietitian
Lysine prevents and reduces cold sores. Read on for how much you need.
Medically reviewed by Femi Aremu, PharmD
Supplemental lysine has been used to prevent and treat cold sores.
Cold sores, also known as fever blisters, are painful blisters on the side of the lips that can open and leak fluid.
The herpes simplex virus causes cold sores. The herpes virus spreads through contact with fluid in open cold sores.
This article reviews research on lysine for cold sores and any safety considerations associated with lysine supplements.
What Is Lysine?
Lysine is an amino acid necessary for human growth, health, and functioning.
Lysine is vital for making protein in the body. It also helps form collagen and supports adequate calcium absorption.
As an essential amino acid, the body cannot produce lysine. Instead, lysine must come from food.
How Much Lysine to Take for a Cold Sore
Most people have the herpes virus, but not everyone will get a cold sore. However, once you get a cold sore, you’ll likely continue getting them.
Additional research is required to determine precisely how much lysine to take for a cold sore.
However, current research suggests dosages ranging from 500–3,000 milligrams (mg) daily, with a general recommendation of 1,000 mg daily to prevent and reduce the likelihood of future cold sores (prophylactic measures).
Higher doses of up to 3000 mg per day may be warranted for a limited time during cold sore outbreaks.
How Does Lysine Work?
Lysine supports collagen and antibody production, helping to repair tissues and fight infection.
Whether lysine works on cold sores is still unclear.
Some research supports the benefit of lysine in reducing the healing time, number, and severity of cold sores.
Older research supports lysine for cold sores. Supplemental lysine of 1,000 mg (1 gram) taken three times daily for six months reduced the number of cold sore infections, symptom severity, and healing time.
Conversely, other research has found no benefit of lysine for cold sores. One small study found no difference in the recurrence of cold sores between participants given lysine supplements or those taking a placebo. Participants took 1,000 mg of lysine daily for six months.
However, despite limited evidence supporting its effectiveness, lysine is still commonly used to prevent and treat cold sores.
For most people, taking 1,000 mg daily of lysine is relatively harmless.
Goodboy Picture Company / Getty Images
Closeup of a Black woman standing in her bathroom holding a vitamin and a glass of waterWhy Do I Need Lysine?
Amino acids and proteins are required for countless bodily functions, including but not limited to the following:
Making neurotransmitters (special brain chemicals)
Making hormones
Repairing and building tissues
Participating in metabolic reactions
Lysine is considered an "essential amino acid." That means you need to get it through the food you eat.
Regardless of overall protein consumption, adequate lysine is necessary for growth and protein balance (also called nitrogen balance).
Dosage or Recommended Dietary Allowance
The Recommended Dietary Allowance (RDA) for lysine varies throughout the life cycle.
The RDA for people 19 and older is 38 milligrams per kilogram (mg/kg per day) or 0.017 grams per pound of body weight per day. As a reference, a person weighing 135 pounds would need 2.33 grams of lysine daily to meet the RDA.
However, the average intake of lysine from food is likely 4 to 5 grams (g) per day for adults with adequate diets.
Protein needs, in general, are higher during pregnancy.
Similarly, lysine requirements increase during pregnancy. The RDA for lysine during pregnancy is 51 mg/kg daily.
Lysine must remain elevated while breastfeeding, with your RDA at 52 mg/kg daily.
What Foods are Rich in Lysine?
Animal-based foods tend to be high in lysine. However, it is possible to meet the recommended lysine amounts on a plant-based diet. Other foods common in a plant-based diet, like beans, are a potent source of lysine.
Foods rich in lysine include but aren't limited to the following:
Chicken breast: 3.08 g per 3.5 ounces (oz) (100 g)
White fish: 1.74 g per 3.5 oz (100 g)
Shrimp: 2.17 g per 3.5 oz (100 g) or 4–6 shelled large shrimp
Pork: 1.92 g per 3.5 oz (100 g)
Beef: 1.42 g per 3.5 oz (100 g)
Soybeans: 2.71 g per 1/2 cup (100 g)
Pistachio nuts: 1.14 g per 2 oz or 100 shelled nuts
Chia seeds: 0.97 g per 1/2 cup
Pumpkin seeds: 1.78 g per 3/4 cup shelled pumpkin seeds
Eggs: 0.92 g per 2 eggs
Beans: 1.48 g per 1/2 cup cooked beans
Lentils: 1.74 g per 1/2 cup cooked lentils
Lysine is the first limiting amino acid in cereal and grain products. Limiting amino acid refers to the protein found in the smallest amount in a food. Grain- and cereal-dominant diets may contain inadequate amounts of lysine.
Special Considerations for Lysine
For most people, lysine may be relatively harmless. However, there are some instances when lysine supplements may not be safe or effective.
Lysine Precautions
Exercise caution when taking lysine supplements if you have any of the following conditions:
Lysinuric protein intolerance: a rare genetic condition in which the body cannot digest and use specific amino acids, namely lysine, arginine, and ornithine.
High cholesterol (hypercholesterolemia): Preliminary animal research shows conflicting results on whether supplemental lysine increases cholesterol levels. More research is necessary.
People with heart disease who are prescribed calcium supplements: Lysine may impact calcium levels by increasing its absorption by the intestines and decreasing its removal by the kidneys. Though animal studies suggest taking calcium and lysine supplements together may be harmful for individuals with heart disease, human studies are necessary to confirm this.
Human immunodeficiency virus (HIV): Lysine has antiviral properties. Individuals with HIV should exercise caution when taking lysine because lysine may increase the amount of the virus (also known as the viral load) in the blood.
Liver (hepatic) or kidney (renal) issues: Lysine is primarily metabolized in the liver and removed from the body via the kidneys. High doses of lysine (such as those found in a supplement) can exert an additional burden on an already impaired liver and kidney.
Pregnancy: Despite the higher needs, limited evidence supports lysine supplements during pregnancy.
Lysine Side Effects
Side effects are related to gastrointestinal issues. Reported side effects include diarrhea, nausea, vomiting, and abdominal pain.
Higher dosages (above 7,500 milligrams daily) are more likely to cause stomach issues, such as diarrhea.
Some severe side effects have been reported, including kidney (renal) dysfunction and failure.
Lysine Interactions
It is not advised to take calcium and lysine supplements concurrently, especially in people with heart disease. Lysine increases calcium absorption while decreasing excretion. This means it causes more calcium to stay in your body for longer.
Arginine (another amino acid) and lysine compete for absorption in the intestines. Consuming significant quantities of lysine (with supplements) can prevent arginine from being absorbed into the body.
When to see a healthcare provider
If you get cold sores, reach out to your healthcare provider about options to reduce pain and duration. Consider talking to your healthcare provider about lysine supplementation and whether it may be a safe and effective treatment for you.
Summary
Lysine is an essential amino acid. Although some research suggests lysine may prevent or reduce the severity of cold sores, data is limited.
If you are prone to cold sores, supplementing regularly with 1,000 mg of lysine may reduce their occurrence. However, limited research is available on taking lysine for cold sores.
Talk with your healthcare provider to see if lysine will be safe and effective for you.
Frequently Asked Questions
How much lysine should a person take for a cold sore?
Based on the available research, supplementing with 1,000 mg daily of lysine may prevent cold sores. Upping the dosage of lysine to 3,000 mg at the onset of a cold sore may reduce its severity and duration.
How long does lysine take to work on a cold sore?
Older research shows supplementing with lysine shortens the duration of a cold sore. Cold sores can last up to 21 days. However, two studies noticed that lysine healed cold sores within six days. Still, additional and more recent research is needed.
What is the best way to prevent a cold sore?
Long-term use of antiviral medication may help prevent cold sores. Cold sores occur due to the herpes virus and spread through contact with fluid in the sore. You can reduce the risk of a cold sore by limiting exposure to this fluid.
Read the original article on Verywell Health.
