Herpes zoster (HZ) is a viral infection that usually presents as a childhood infection of varicella (i.e., chickenpox). The pathogen is human herpesvirus-3 (HHV-3), also known as the varicella zoster virus (VZV).
Following the acute phase, the virus enters the sensory nervous system, where it is harbored in the geniculate, trigeminal, or dorsal root ganglia and remains dormant for many years. With advancing age or immunocompromised states, the virus reactivates and an eruption (i.e., shingles) occurs.
Even after the acute rash subsides, pain can persist or recur in shingles-affected areas. This condition is known as postherpetic neuralgia (PHN).

Treatment
- A live-attenuated varicella-zoster virus vaccine is effective against herpes zoster (HZ) and postherpetic neuralgia (PHN). The the main benefit of HZ vaccination is prevention of morbidity caused by pain.
- Zostavax may significantly reduce the risk of developing zoster by approximately 70%.
- Restoration of vitamin C concentrations decreases spontaneous pain (but not brush-evoked pain) by 3.1 on a numeric pain scale.
- Lidocaine 4% ophthalmic drops administered to patients with ophthalmic postherpetic neuralgia may produce a significant reduction in eye and forehead pain.

See the reference for more information.

Adapted from Medscape Drugs & Diseases. Postherpetic neuralgia treatment & management. Available at http://emedicine.medscape.com/article/1143066-treatment. Accessed on February 15, 2016. To view the entire article and all other content on the Medscape Drugs & Diseases site, a free, one-time registration is required.