Two types of mouth sores are fairly common: cold sores and canker sores. Cold sores, also known as fever blisters 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.

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.