Cold : 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. 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" 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. Even though most genital herpes is caused by hsv-2, we do see genital herpes caused by hsv-1 - most likely from oral sex. This is less common, though.
Answered 10/3/2016
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