Cold sores, or fever blisters, result from a viral infection. These painful, fluid-filled blisters commonly appear on or near the lips in clusters or patches. Cold sores are caused by the herpes simplex virus type 1 (HSV-1, also known as oral herpes). HSV-1 can be spread through close contact, such as kissing.

There is no cure for a cold sore infection, but this condition can be treated with common antiviral medication, such as valacyclovir (Valtrex) or acyclovir (Zovirax). A medication you might take in addition to antivirals is lysine, an essential amino acid found in protein. It isn't produced in your body, so you must consume it through an oral supplement or diet.

Common foods rich in lysine include:

beef
chicken
turkey
pork
codfish
sardines
eggs
yogurt
parmesan cheese
spirulina
soybeans

Lysine is essential for human health, aiding calcium absorption and collagen formation. Many people consume enough lysine in their diet. But some — athletes or vegans specifically — may need to consume more. If you don't have enough lysine in your body, you may experience irregular symptoms, including:

fatigue

nausea

appetite loss

agitation

anemia