Fever blisters, also known as cold sores, are caused by a herpes virus and occur on the outside of the lips and face. Painful and unsightly, cold sores generally go away in about a week. Oral prescription medication and over-the-counter creams seem to help clear up the infection sooner.
Are fever blisters or cold sores the same thing as canker sores?
No. Canker sores occur inside your mouth. They are very painful but usually go away in a week or two. It is unclear as to what causes these sores but a weakened immune system may be one of them. Stress and fatigue seem to be a couple of the triggers that bring them on. Some people are sensitive to a common ingredient used in toothpaste, sodium laurel sulfate (SLS). There are a couple of toothpastes that are SLS free. Anesthetic creams can help reduce the symptoms. While the canker sore is healing, it is best or avoid spicy or acidic foods.