Cold sores, also known as fever blisters, are small, fluid-filled blisters that typically appear on or around the lips and mouth. They are caused by the herpes simplex virus (HSV), most commonly HSV type 1, although HSV type 2 can also lead to outbreaks. Cold sores usually begin with a tingling or burning sensation before the blisters form. The sores can be painful and may last for about 1 to 2 weeks before they crust over and heal. Cold sores are highly contagious and can be spread through direct contact with an infected person or by sharing items like utensils, lip balm, or towels. While there is no cure for the herpes virus, antiviral medications and over-the-counter treatments can help reduce the severity and duration of outbreaks. Avoiding triggers such as stress, illness, and excessive sun exposure can also help prevent future outbreaks.