A cold sore is a cluster of small, fluid-filled blisters that typically appear on or around the lips but can also form on the nose, cheeks, chin, or inside the mouth. These sores are caused by an infection with the herpes simplex virus, most commonly herpes simplex virus type 1 (HSV-1), though HSV-2 can also cause them. Cold sores are also known as fever blisters or herpes labialis

. The infection usually remains dormant in the nerve cells after the initial outbreak and can reactivate periodically, leading to new cold sore outbreaks. Cold sores often start with a tingling, itching, or burning sensation around the affected area, followed by the appearance of painful blisters. These blisters eventually burst, ooze fluid, crust over, and heal within about 2 to 3 weeks without scarring

. Cold sores are highly contagious and spread through close personal contact such as kissing or sharing utensils, towels, or other items that come into contact with the infected area or bodily fluids. While there is no cure for cold sores, antiviral medications and creams can help speed healing and reduce the frequency and severity of outbreaks

. In summary, a cold sore is a contagious viral infection characterized by painful blisters around the mouth caused by the herpes simplex virus, with symptoms progressing through stages of tingling, blistering, oozing, crusting, and healing over a couple of weeks