Herpes zoster, colloquially known as shingles, is the reactivation of varicella zoster virus (VZV, primary infection of which leads to chickenpox), one of the Herpesviridae group, leading to a crop of painful blisters over the area of a dermatome. In Italy and in Malta, it is sometimes referred to as "St. Anthony's fire". [1] Shingles incidence is high in the elderly (over 60), as well as in any age group of immunocompromised patients. It affects some 1 million people per year in the United States and can involve excruciating pain.

The earliest symptoms of shingles include headache, sensitivity to light, flu-like symptoms without fever, as well as itching, tingling, and extreme pain where the rash is developing. Often, pain is the first symptom. This pain can be characterized as stinging, tingling, numbing, or throbbing, and can be pronounced with quick stabs of intensity. Then 1-3 crops of red lesions develop, which gradually turn into small blisters filled with serous fluid. A general feeling of unwellness often occurs. In some cases, the rash does not form blisters, but has an appearance much like urticaria ("hives").