What are the symptoms of cold sores and what should I do to help?

Painful blisters. Cold sores are painful blisters on or near the lips, cause by a herpes virus. They can come and go, since the body never completely gets rid of the virus. For many people with cold sores, topical over the counter treatments for pain relief are enough. If not, topical or oral antiviral medications can help if started soon after the cold sore first appears.