(HealthDay News) -- A cold sore is a painful sore that often forms on the lips or around the mouth. While a cold sore is caused by the herpes virus, many factors can act as triggers.
The American Academy of Dermatology says potential triggers include:
- Feeling run down, stressed or tired.
- Having the flu, a fever or a cold.
- Being exposed to the sun.
- Having hormonal changes as a result of pregnancy or menstruation.
- Having an injury or trauma to the face from a cut, dental work, shaving or surgery.