Cold sores are caused by a virus, the herpes simplex virus, or HSV. There are two types of herpes simplex virus, called type 1 and type 2. While both types can cause cold sores, type 1 is the variety generally responsible. HSV type 2 is found in genital herpes and is much rarer than HSV type 1.

HSV-1 is the most common cause of cold sores. Most people are exposed to HSV-1 between the ages of three and five. There are many ways a person can become infected with HSV-1, including coming into close contact with a person who has a cold sore, drinking contaminated fluids that have been sneezed or coughed in the air, or coming into contact with Objects that a person with a cold sore touched or used. Although most people are first infected with the HSV-1 virus at a young age, they don’t get their first cold sore until after puberty. Once someone is infected with HSV-1, the virus stays with them for the rest of their life.

HSV-2 is much less common than HSV-1. It mainly causes genital herpes. HSV-2 generally only affects parts of the body that are below a person’s waist, but in rare cases, it can cause a person to get cold sores.

Once a person is infected with HVS-1, several things can cause cold sores. A bad cold, a case of the flu or any type of illness that affects the immune system can cause the appearance of cold sores. Extremely chapped or sunburned lips can increase the chance of a cold sore outbreak. Women who are pregnant or menstruating are also at increased risk for cold sores.

But cold sores are not caused only by physical factors. Emotional stress or prolonged discomfort is another factor that can lead to a cold sore outbreak. Another factor that has been seen to increase the risk of an outbreak is physical stress or fatigue. All of these stressors weaken the immune system, making it difficult for the body to fight the flare-up.

Many people experience cold sores only a few times in their life, while others get it much more often. There is no cure for cold sores. And with so many different causes that people have no control over, treatment and therapy by trained professionals are often the best ways to manage troublesome flare-ups.