A cold sore is an inflamed blister in or near the mouth that is caused by an infection of the herpes simplex virus (HSV-1). Oral herpes spreads through close personal contact, such as kissing, which then causes tiny fluid-filled blisters, which can reoccur. However, medications can speed up the healing process and reduce recurrence.
Cold sores are not generally serious, but the infection may be life-threatening for someone who has a weakened immune system.
Using valacyclovir or another antiviral drug like acyclovir can be taken to prevent cold sores. This helps reduce the chance of getting a cold sore. It may also help if you avoid triggers, such as sun or wind exposure that can activate the cold sore virus.
How long are cold sores contagious?
Cold sores that are caused by herpes simplex type 1, are contagious until they completely go away, which usually takes about two weeks. They are most contagious when fluid seeps out of the sores.