Post herpetic neuralgia is a nerve disease occurs after an attack of herpes zoster infection. Herpes zoster or ‘shingles’ is a viral infection which affects the skin, especially sides of the chest, caused by the varicella-zoster virus. This is the same virus which causes chickenpox in children.

After an episode of herpes, the virus remains dormant in the nerve tissues of the body. This virus may become active when the immunity of the individual reduces or during convalescence after a major illness, resulting in blisters on the skin, known as shingles. It is accompanied by a rash which disappears without major consequences in about two to four weeks. Around 50% of individuals with shingles go on to develop post herpetic neuralgia (PHN) or after-shingles pain.

The neuralgia begins when the herpetic eruptions begin to heal. The pain appears usually in the affected dermatome or the affected nerve course and results in severe pain in the region which has the same nerve supply. The pain is a drawing, pricking type of intense pain, sometimes accompanied by burning sensation of the skin. The pain lasts from a few weeks to a few months, rarely years.