It begins with a tingle, an itching or an odd sensation on the lip. Experienced sufferers know that the weird feeling is the first step in an uncomfortable and unsightly cold sore. These skin eruptions are different from canker sores--also called recurrent aphthous ulcerations--which occur inside the mouth, according to the Cleveland Clinic. Cold sores on the lips and surrounding skin are very common.
Viruses
Cold sores are caused by the herpes virus. The American Academy of Dermatology notes that there are two types of viral herpes, Herpes simplex virus type 1, or HSV Type 1 and HSV Type 2, which is a sexually transmitted disease. HSV 1 causes clear blisters that are filled with fluid and form on the outside of the mouth and under the nose and lips.
Types of HSV 1
HSV type 1 infections are classified as primary or recurrent. The primary infection of the virus sometimes erupts in skin or around the mouth but often there is no obvious symptoms with initial infection, according to HerpesGuide.ca. The primary infection is the onset of the virus and is caused by transmission from person to person, just like other viruses. Once infected, a person will always have the virus. After the primary infection, the virus becomes dormant. The recurrent or secondary infections occur when the viruses flares up and becomes active.
Transmission
Even though herpes infections are extremely contagious, the AAD also notes that only about 10 percent of infected people actually develop sores. HSV type 1 is spread through contact. Most people get the virus when they are children although infection can occur at any age. The infection spreads easily, usually between family members or friends. Sharing towels, silverware, food and drinks and kissing are all ways the virus spreads. Stress, trauma and sun exposure cause secondary eruptions but sometimes the subsequent cold sores erupt for no reason.
