Cold sores, also known as fever blisters, are common outbreaks that usually appear on the lips. Sometimes they can show up on the nostrils, chin or fingers, according to MayoClinic.com. They are not the same as canker sores, which usually appear on the inside soft tissue of the mouth. Cold sores rarely appear inside the mouth, but if they do, it is usually on the gums or the roof of the mouth.
Cause
The herpes simplex 1 virus is the usual cause for cold sores. The herpes simplex 2 virus is often the cause of genital herpes. Either virus can cause sores on the facial or genital area. Most people eventually get infected with herpes simplex 1, but only about 10 percent develop the sores, according to the American Academy of Dermatology (AAD).
Outbreak
Sores may appear two to 20 days following contact with an infected person. The skin may first begin to itch, sting, burn or tingle, the AAD explains. The blisters are tiny, clear and filled with fluid. The blisters may break and crust before falling off. The infection can last seven to 10 days.
Recurrence
The skin clears up, but the virus remains in the body in a dormant state. It can recur in the same location every few weeks or never at all, the AAD says. A recurrence is usually milder than the first outbreak. Recurrent sores may reappear for no reason or from such factors as fever, sun exposure, menstrual periods or trauma.
Infection
Cold sores can be passed on through skin-to-skin contact. The sores are contagious from the time the blisters appear until they have completely dried and crusted. But the infection can spread even after healing of the skin. People with active cold sores should avoid close contact with infants, advises MayoClinic.com. Others who are at higher risk for catching the infection include people with eczema or those with suppressed immune systems. Infected individuals should avoid sharing items such as utensils and towels or any item that might spread the virus to others. They should also wash their hands frequently to avoid spreading the virus when touching people.
Treatment
Cold sores usually clear up on their own, but over-the-counter ointments and pain relievers can ease discomfort. Recurrent outbreaks may be prevented by using sun block on the lips and face during prolonged exposure to the sun. Dr. Andrew Weil, noted nutritionist, recommends avoiding foods rich in the amino acid arginine, which may activate the virus. These foods include chocolate, colas, beer, seeds, nuts and peas. It is also a good idea to get a new toothbrush after an infection heals, he says. The virus can remain in the toothbrush and reinfect the person.
