We've all seen someone with it.  Or maybe you've got it yourself.  The dreaded cold sore on the corner of the lip.  It warns you it's coming with a tingling and burning feeling, then the painful blisters arrive and often outstay their welcome.  So what's the deal with these cold sores?  Where do they come from?

A virus called herpes simplex virus (HSV) is responsible for causing cold sores, also referred to as fever blisters.  It most commonly occurs in young adults, but can be seen at any age, including infancy.  Many people are infected with the virus and never develop cold sores.  Others may have sores but they aren't painful or symptomatic.  And yet others will have fever, headache, or pain associated with the blisters.

80-90% of herpes infections seen on the lips are caused by HSV type 1, and 10-20% are caused by HSV type 2.  Genital herpes is usually reversed, with 70-90% caused by HSV-2, and 10-30% caused by HSV-1.  But this is not a hard and fast rule; either type can be seen with lips or genitals.

So how is this virus spread?  Usually skin-skin contact is required.  The virus is shed in skin or secretions.  When herpes is seen in wrestlers due to skin-to-skin contact, it's called herpes gladiatorum, and is more common on the head, neck, or shoulder.

Unfortunately, once you've contracted HSV, it's there for life.  (So what happens in Vegas doesn't always stay in Vegas...).  It stays dormant in the nerves and gets reactivated later on.  About 1/3 of people with cold sores on the lips will have a recurrence.  And of these, 1/2 will have at least two recurrences annually.  Usually there is a precipitating factor to bring it out: sunburns/sun exposure, fevers/colds, stress, and altered hormones. 

Before we discuss treatment, let's talk prevention.  Avoid skin-to-skin contact with an area during an outbreak.  The outbreaks are usually treated with oral antiviral medications such as acyclovir, valcyclovir (valtrex), or famciclovir.  If the outbreaks are very frequent, daily suppressive therapy may be used.  There are topical presciption creams, as well, but they are typically not as effective as the pills.  The medications work best if they're used as soon as the tingling/burning feeling comes on.  Although there's no cure, with today's treatments, the discomfort can be minimized and sometimes prevented.