Cold sores

Cold sores are small, fluid-filled blisters that typically appear around the lips and mouth. They are caused by the herpes simplex virus (commonly type 1). After initial infection, the virus remains inactive in nerve cells and can reactivate later, often triggered by stress, illness, or sunlight. During outbreaks, sores may be painful or itchy and eventually crust over and heal. Cold sores are highly contagious, especially when blistered, and can spread through close contact. While they usually resolve on their own within a couple of weeks, antiviral medications can help reduce their severity and frequency.