Lysine is not a cure for cold sores, but it may help prevent and shorten the duration of an outbreak. A person should continue to take any antiviral medications a doctor prescribes for their cold sores. Those interested in adding lysine supplements to their routine should speak to their doctor beforehand.

Vitamin B deficiency has been linked with cold sore outbreaks. There are actually eight distinct vitamins in the B family — thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, and cobalamin — which are responsible for promoting a strong immune system and healthy cell growth.

For cold sores (herpes simplex labialis): 1000 mg of lysine taken daily in up to two divide doses for up to 12 months, or 1000 mg taken three times daily for 6 months has been used. For preventing cold sores from recurring, 500-1248 mg taken daily or 1000 mg taken three times daily has been used.

Taking lysine supplements is very safe and does not seem to cause many side effects. Most people can take a daily dose of up to 3 grams (g) of lysine without any side effects. Increasing the dosage of lysine to 10–15 g a day may result in digestive issues, such as: diarrhea.

But for people affected with the herpes simplex virus, too much sun or vitamin D can actually increase the chance of cold sore outbreaks, and in many cases, make the outbreaks worse than normal. Does That Mean That You Should Stop Taking Vitamin D if You Suffer from Herpes?

Good sources of lysine include foods that are rich in protein, such as:

• Meat, specifically red meat, pork, and poultry.
• Cheese, particularly parmesan.
• Certain fish, such as cod and sardines.
• Eggs.
• Soybeans, particularly tofu, isolated soy protein, and defatted soybean flour.
• Spirulina.
• Fenugreek seed.

To treat a cold sore infection, apply lysine cream to the affected area every two hours for 11 days. To manage cold sore infections, the recommended dosage for oral supplements is 1 gram three times daily.

Lysine is thought to interfere with arginine being absorbed into your intestine, making the amino acid unavailable for the virus. So even if it may not cure a cold sore infection, lysine can help slow or prevent the HSV-1 replication process. suggests that lysine may reduce the number of occurrences of this infection and decrease healing time .

Cold sores, also known as fever blisters, can be uncomfortable as well as embarrassing. There are several vitamins which can be used to help prevent or treat this condition. Some of the most commonly used vitamins for cold sores include lysine, zinc oxide, and Vitamins A, B, C, and E.

The common dosage of lysine for cold sores is 1,000 mg three times a day with meals. Do not take more than 3,000 mg daily. Once the lesions clear, drop your dose to 500 mg daily to prevent them from coming back. If you experience a repeat outbreak, increase to 1,000 mg daily until the lesions clear and do not return.