Bio Andrew âAndyâ Lambros is a web and graphic designer, developer, marketing expert and business consultant. He is the Co-founder and President of the Dream Builders Company, located just outside of Los Angeles, in Southern California.
I have a 3 year old with a sore in his mouth. It is between his upper lip and his gums at the very top. It looks like a white circle and it has a red streak coming down to his teeth.
How Long Do Cold Sores Last? Herpes-induced cold sores, also known as fever blisters, often break out on the lips or in the mouth. According to the NHS, untreated cold sores take approximately seven to ten days to heal. Medical specialists at the University of Maryland Medical Center believe that they last between two and three weeks, with some sores in people with weakened immune system lasting as long as six weeks.