Cold sores or fever
blisters are caused by herpes simplex virus
type 1 (hsv
-1) and are extremely common. Most people become infected as an infant or small child when kissed or by sharing eating utensils with an adult who has the virus. 20% of the cases of genital herpes
are also caused by hsv-1 thought to be infections from oral-genital contact. The virus is most contagious when someone has a cold sore
, but can still be passed along by someone who does not. Many people do not even know that they are infected because the virus can "hide out" in the nerve
cells for very long periods of time - for some people it hides out forever and they never get a cold sore. For others, the virus can "wake up" at any time and that's when a cold sore happens. No one knows exactly what causes a cold sore to appear - sometimes stress
, illness, fevers, colds, sunlight, cold weather, menstruation
, certain foods, allergies
, you name it! they usually last 7-10 days and are more of an annoyance than a danger unless you have a weakened immune system or contract a bacterial infection on top of the cold sore.
Legal disclaimer: I am providing this general and basic information as a public service and my response to this question does not constitute a doctor-patient relationship. For any additional information, advice, or specific concerns, please speak with your own physician. The information provided is current as of the date of the answer entry.