Cold sores result from a recurrent viral infection caused by the herpes simplex 1 virus. They are characterized by reddish blisters around the mouth. The virus remains permanently in the system, sitting dormant in the nervous tissue near the lips, periodically emerging to cause symptoms. Cold sore flares are typically brought on by stress, compromised immunity, sun exposure, other viral infections, menstruation, allergic reactions, or high amounts of the amino acid arginine in the diet. Nearly 90% of adults show past virus exposure, typically encountering it in childhood, but not everyone expresses symptoms. A diet that strengthens the immune system while emphasizing lysine and reducing arginine has shown significant benefits in reducing outbreaks and viral transmission.