Each year approximately 1,000,000 people in the U.S. develop shingles or herpes zoster. Of these, it is estimated approximately 10-20% (about 200,000) will go on to develop PHN.
The incidence of postherpetic pain generally decreases steadily over the first year after the initial herpes zoster outbreak, subsiding quickly in most patients and showing a progressive reduction in pain in others. (Koltzenburg, 2001). Thus while up to 20% of untreated patients have persistent pain one month after healing of an acute herpes rash, only between 4-22% of these patients will still experience pain more than a year later.
The risk of developing PHN increases with age and can affect at least 40% of all herpes zoster patients over age 50 and 75% of herpes zoster patients over age 75 (Vander Straten, 2001). PHN is the single most common neurologic condition in elderly patients (VanderStraten, 2001).