Cold sores are small blisters that develop on the lips or around the mouth. They're caused by the herpes simplex virus and usually clear up without treatment within 7 to 10 days. Cold sores often start with a tingling, itching or burning sensation around your mouth. Small fluid-filled sores then appear, usually on the edges of your lower lip. Read more about the symptoms of cold sores. If you've had outbreaks of cold sores before, it's likely that you'll know what they are if they return. You only need to visit your GP if you're unsure whether it's a cold sore or if it's severe and spreading further than just the lip.

Skip navigation! Story from Sex. Cory Stieg. Pesky little cold sores love to sprout up at the most inconvenient times, huh? Maybe you got yours right before your wedding, the first day at a new job, or — perhaps the most infuriating — the night when you were finally planning to seal the deal with a new sexual partner.

Cold sores are small, fluid-filled blisters that usually appear on or around the lips and mouth. They can appear on their own or in small clusters. In most cases, the blisters will break, creating a scab that eventually falls off. Cold sores are caused by the herpes simplex virus type 1 HSV HSV-1 is very contagious.