Postherpetic neuralgia (PHN) is the most common complication of herpes zoster or shingles. It is defined broadly as any pain that remains after healing of herpes zoster lesions or rash, usually after a three month period. Shingles (also known as herpes zoster) is a skin rash that can be very painful.
It is a viral infection of the nerves, and the nerves affected by shingles can occasionally continue to cause severe pain after the shingles have cleared. Shingles appear as a rash, patch, or a line of painful blisters which arise on the skin over a nerve in the shape of a band.
This band follows the distribution of a specific nerve where the virus has been living before its spread to the skin. Shingles affects both men and women equally. This disease is caused by the same virus that causes chicken pox (varicella zoster).