A. Cold sores (or fever blisters) are caused by the very common herpes simplex virus.  According to the American Social Health Association, over 50 million Americans have oral herpes.  In some people the virus lies dormant over a lifetime.  Others have frequent outbreaks.  Herpes simplex is spread by direct skin-to-skin contact.  If your partner has a cold sore and kisses you, she can spread it to your mouth.  If she puts her mouth on your genitals (oral sex), she can give you genital herpes.  Over 30 million American are estimated to have genital herpes. 

There are two types of the herpes simplex virus-herpes simplex type 1 (HSV-1) and herpes simplex type 2 (HSV-2).  These viruses look identical under the microscope, and either type can infect the mouth or genitals.  HSV-1 is most likely to occur on the mouth, while HSV-2 usually occurs below the waist.  It really doesn't matter which type a person has because both types cause the same symptoms.

The health effects of herpes (both oral and genital) vary from person to person.  For many, the sores may occur less than once or twice a year, causing no more than a minor irritation with itching and tingling.  For others, herpes causes more frequent outbreaks with painful blisters.  While herpes is not curable (the virus stays inside a person for life) there is a prescription drug called acyclovir that helps to control outbreaks.  Even without medication, herpes is usually quite manageable.