What is the difference between mouth ulcer, canker sore, cold sore, and stress sore?

Mouth sores: All of these types are related to the fact that viruses are present at all times and when the patient is susceptible, i.e., tired, under stress, not eating well, etc, the ulcer appears. Antiviral drugs may helpful but they need to be taken at the first symptoms, abreva is an oct medication that can be purchased and applied with q-tip to the affected lip area. See your dentist if needed.