Herpes zoster is caused by the same virus that causes chickenpox. Therefore, a person who has never been exposed to this virus can develop chickenpox when exposed to a patient who has blisters of herpes zoster.
Once a patient recovers from chickenpox, the virus lies dormant in a small part of the spinal cord (the dorsal root ganglion). For some reason, when the body resistance goes down, this virus re-activates and presents itself in the form of herpes zoster. Normally, herpes zoster occurs only once in a lifetime, unless the person has severe immunodepression, for example, in AIDS. In elderly patients, one would like to exclude an underlying predisposing factor like malignancy.
Pain is an important component of this disorder. Post herpetic neuralgia can be very severe. To minimise the frequency and the severity of this neuralgia, the specific antiviral medicine should be started within the first 48 hours, at the most within first 72 hours. Greater the age at which herpes zoster occurs, greater is the probability for severity and occurrence of neuralgia. Once it occurs, it will take its own time to go; this varies from person to person. Medicines are given to make the patient comfortable. In a rare case, one may have to block the nerve of the area.