Cold sores, which are small and somewhat painful blisters that usually show up on or around a person’s lips. Cold sores are caused by the herpes simplex virus-1 (HSV-1). But they don’t just show up on the lips. They can show up inside the mouth, on the face, or even inside or on the nose. These places are the most common, but sores can appear anywhere on the body, including the genital area.
Genital herpes isn’t typically caused by HSV-1; it’s caused by another type of the herpes simplex virus called herpes simplex virus-2 (HSV-2) and is spread by sexual contact. But even though HSV-1 typically causes sores around the mouth and HSV-2 causes genital sores, these viruses can cause sores in either place.
What Causes a Cold Sore?
HSV-1 is very common. If you have it, chances are you picked it up when you were a kid. Most people who are infected with the herpes simplex virus got it during their preschool years, most likely from close contact with someone who has it or getting kissed by an adult with the virus.
Although a person who has HSV-1 doesn’t always have sores, the virus stays in the body and there’s no permanent cure.
When someone gets infected with HSV-1, the virus makes its way through a microscopic tear in skin and into a group of nerve cells called a ganglion. The virus moves in here, becomes inactive or dormant, and every now and then decides to become active and cause a cold sore. Not everyone who gets the herpes simplex virus develops cold sores. In some people, the virus stays dormant (asleep) permanently.
What causes the virus to become active? The truth is, no one knows for sure. A person doesn’t necessarily have to have a cold to get a cold sore — they can be brought on by other infections, fever, stress, sunlight, cold weather, hormone changes in menstruation or pregnancy, tooth extractions, and certain foods and drugs. In a lot of people, the cause is unpredictable.