Conditions list medically reviewed by George Krucik, MD, MBA
The herpes simplex virus (HSV) is an infection that causes herpes. Herpes appears most often on the genitals or mouth.
A canker sore, or aphthous ulcer, is a mouth ulcer or sore that's open and painful. It's the most common type of mouth ulcer.
This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.