Cold sores are also called mouth herpes, fever blisters or herpes labialis. They are painful blisters that are situated on the lips, mouth or areas around the mouth and face. The infection is caused by the Herpes simplex virus. There are two types of Herpes simplex viruses. Type 2 causes most cases of cold sores, while type 2 also called genital herpes, commonly affects the vagina or penis in men.
Up to 8 in 10 herpes infections do not present with symptoms, but when symptoms occur it cause blisters with
fever and enlarged lymph nodes.

Outbreaks of cold sores occur as a result of reactivation of the latent virus to an active form in the body. There are several factors that can trigger an outbreak of cold sore. Among these factors are decreased levels of immunity due to illness, exposure to sunlight, excessive amounts of stress and consumption of certain foods.
Reactivation of the herpes virus may occur after a trigger event that causes the virus to transform from dormant to active. Some of the foods to avoid decreasing the risk of viral reactivation are explained below.

Acidic food
At the time of crusting when the blisters in the mouth broke down. Certain food can exacerbate the symptoms of pain and discomforts and should be avoided. Some acidic foods to avoid are citrus fruits, fruit juices, wine, soda and vinegar. There is a need to reduce salty and spicy food.
Some foods to avoid are: citrus fruits, tomatoes, fruit juices, wine, soda, pickles, and vinegar-based salad dressings
Arginine-rich food
In research conducted by Richard showed the amino acid arginine support the growth of the herpes simplex type I virus. The virus requires arginine for its growth and replication. However, the presence of lysine suppresses the growth of the virus. Lysine competes with arginine for transport across the intestinal wall. The net result is decreased level of arginine, thus suppressing the growth of the viruses.

Food that contains a high amount of arginine that should be avoided if you have cold sore include: peanuts, peanut butter, chocolates, pumpkin seeds, soybeans and lentils. Avoid such drugs during an outbreak of cold sore.
A healthy balanced diet with a complete supply of vitamins, essential nutrients and minerals with a high amount of lysine and a low amount of arginine can help.
Foods with a high amount of lysine and low arginine include
Fish especially sardines and cod
Meat such as beef and chicken
cheese, yoghurt and dairy products.
Fruits such as pears, apples.

Another alternative is to use lysine supplements. Which provide a supply of amino acid to significantly reduce the symptoms of the infection.
Processed food
Some processed food can suppress the immune system and may not be good especially during the active phase of the infection. Eat a healthy balanced diet and avoid sugary foods