Cold Sore

Cold Sore, also called fever blister, a small, painful blister on the face, especially around the lips and nose and inside the mouth. A cold sore first appears as a small red pimple that gradually develops into a small, painful blister full of clear fluid. When the blister ruptures, it appears yellowish, dry, and crusted. Cold sores are caused by a herpes simplex virus. They spread from one individual to another by direct contact between skin surfaces, and they usually erupt in clusters.

Most people infected by the herpes simplex virus contract it before adolescence, but only a small percent of exposed children actually develop symptoms at that time. When the herpes simplex virus is inactive, it lies dormant in neurons, or nerve cells. Later, illnesses or emotional upsets can reactivate the virus and trigger the development of cold sores, and affected individuals often suffer from recurring attacks. Cold sores tend to accompany common colds and infectious diseases, such as pneumonia and diphtheria, that are characterized by fever. The cold sore infection itself can raise body temperature above normal and account for swelling in the lymph nodes of the neck. Cold sores usually last from ten days to two weeks, and no preventive measures are known, although complications caused by the bacterial infections that often accompany cold sores can be controlled by antibiotic ointments. The antiviral ointments known as vidarabine and acyclovir may also be prescribed to relieve the pain of cold sores.