Causes of fever blisters, oral herpes, or cold sores

Q: What causes Cold Sores, Fever Blisters or Oral Herpes?

Although Oral (cold sores) and Genital Herpes are typically area-specific, herpes infections can occur anywhere on the body. Inadvertent touching of an HSV sore during the first episode of infection, followed by touching another part of the body can spread the infection to less traditional locations. Once infection has been established in an area, it can recur in the same place. Accidental infection of another part of the body is less common in people with a history of cold sores, but it can happen. People who get cold sores should take care not to touch other parts of the body after touching a cold sore. .Medical scientists who study herpes have written that a combination of education and effective products to control cold sores may help prevent the transmission of the cold sore virus to the genital area.

The other Herpes group of viruses are the Varicella-Zoster virus which causes chicken pox in children and shingles (herpes zoster) in older people, the Epstein-Barr virus which causes infectious mononucleosis (mono) and cytomegalovirus (CMV) which causes infections in newborns and people with defective immune systems.

Q: What causes a recurrent cold sore outbreak?

Following the primary infection, the herpes virus becomes latent (it goes to sleep) deep inside nerve cells. Scientists are not yet sure why some people have many cold sore recurrences per year and yet others seem to be protected and may not get lesions as often or at all. Recurrent infections can be triggered by many different stimuli. The most common “cold sore alarm clocks” are fever (ergo “fever blister”), and exposure to the sunlight (UV-B).

Other stimuli include localized trauma to the mouth (such as dental work and cosmetic procedures to the face), other illness, and emotional stress.  For some individuals, recurrences are unpredictable and have no recognizable cause. In fact, some literature suggests that the viral DNA may trigger itself. Others are very aware of what kinds of events will likely lead to recurrences and can anticipate the need to begin treatment as early as possible in an acute episode.

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