Herpes

Cold sores, also known as fever blisters, are small, fluid-filled blisters that typically appear around the lips in clusters. They usually heal within 2 to 3 weeks without leaving scars. Cold sores are highly contagious and spread through close contact like kissing, often caused by the herpes simplex virus type 1 (HSV-1), and less commonly by HSV-2. The virus can also spread through oral sex. It can be transmitted even when sores aren't visible. Once infected, the virus remains in the body for life, often dormant but can reactivate and cause outbreaks.