Postherpetic Neuralgia

Postherpetic neuralgia is pain that persists after an episode of shingles (herpes zoster) has resolved. Usually, the pain develops during an episode and continues. But occasionally, the pain starts 4 months or more after an episode has resolved.

Shingles is a painful skin rash caused by reactivation of the virus that causes chickenpox (the varicella-zoster virus). In many people, the pain of shingles gradually goes away over a period of a few weeks to a few months. But shingles leads to postherpetic neuralgia in up to half of people over 60 and up to three fourths of people over 70.

Postherpetic neuralgia lasts longer and is more severe in older people. It is more likely to develop if pain occurred before the skin rash of shingles appeared, if pain was severe while the rash was present, or if shingles affected the eyes (causing a rash on the tip of the nose or making the eyes inflamed and red). Postherpetic neuralgia is also more likely to occur if the immune system is weakened. Taking chemotherapy drugs or drugs that suppress the immune system (immunosuppressants), such as cyclosporine and corticosteroids, can weaken the immune system.

Symptoms and Diagnosis

Postherpetic neuralgia may be a constant deep aching or brief bouts of burning, excruciatingly sharp pain. The pain may feel like an electric shock. Pain may come and go. It may be easily triggered, for example, by a light touch or a change in skin temperature.

Constant or unpredictable pain can be very disruptive, affecting nearly everything a person does. Wearing clothing, particularly fitted clothing, or taking a bath can cause agonizing pain. The pain may interfere with sleeping. Some people stop driving because they fear an attack of pain might occur and cause an accident. Thus, postherpetic neuralgia can sometimes lead to social isolation or depression.

The diagnosis is based on symptoms and a history of having had shingles. Doctors ask what the pain feels like, where it occurs, and when it started (particularly in relation to having a skin rash).

Treatment and Outlook

Relieving the pain of postherpetic neuralgia is difficult. Typical pain relievers, such as acetaminophen or ibuprofen, may be tried, but they usually do not provide enough relief. Creams or lotions containing capsaicin (a substance in hot red peppers) are often used to relieve pain and are often effective. Lidocaine, a type of anesthetic, can be applied to the skin as a gel. It usually helps. Gabapentin (an anticonvulsant) may effectively relieve pain.

Postherpetic neuralgia often disappears, even without treatment, within a year. However, in up to half of people over 70, it persists.