A new study offers insights into what helps -- and what does not help -- relieve long-lasting shingles pain.

Doctors call it postherpetic neuralgia or PHN. It's caused by nerve damage left behind by a case of shingles. Shingles itself comes from reactivation of a chickenpox virus, varicella zoster. The virus travels down nerve fibers to cause a painful skin rash.

When the rash goes away, the pain usually goes with it. But for 12 percent to 15 percent of people the pain remains. If your shingles pain lasts eight to 12 weeks after the rash goes away, you're part of an "unfortunate minority," says pain researcher Andrew S.C. Rice, MD, of Imperial College, London.

"Among people with PHN, some have their pain resolve in the first year to 18 months after the shingles rash goes away," Rice tells WebMD. "But if they have pain longer than that, it is not going to go away on its own. In either case, a person must deal with the pain."

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Treating the Pain of PHN

Exactly how best to deal with the pain is a difficult question. Rice led a research team that looked at 35 clinical trials of various treatments. The findings appear in the July issue of the free-access online journal PloS Medicine.

"The most important thing to realize is these are painkillers," Rice says. "You are treating the pain, not the disease itself. And this is due to permanent nerve damage. It is like a stroke. We can't make the nerve damage better, but we can treat the disability. And for PHN, pain is one of those disabilities."

What helps? Rice's team found good evidence supporting:

-- Tricyclic antidepressants. These are the older kinds of antidepressant. Those shown effective for postherpetic neuralgia include nortriptyline (Pamelor), desipramine (Norpramin), and amitriptyline (Elavil, Endep).

-- Strong opioids. Those shown effective for postherpetic neuralgia include morphine, oxycodone, and methadone.

-- Neurontin

-- Lyrica

-- Ultram, Ultracet

-- Lidoderm

-- Zostrix

What does not work? Rice notes that it's hard to say something never works for anyone. And for some treatments there simply isn't enough evidence to say they work. But his team found that the available evidence does not support the use of:

-- A group of drugs called NMDA receptor antagonists. These include oral memantine (Namenda), oral dextromethorphan, and intravenous ketamine.

-- Codeine

-- Ibuprofen (Advil, Motrin)

-- Lorazepam (Ativan)

-- Triptans (migraine drugs)

-- Zovirax

-- Topical benzydamine (Tantum)

-- Topical diclofenac (Solaraze)

-- Vincristine iontophoresis

Read WebMD's "Is Shingles Contagious?"

Combining Treatments

Rice's report fits very well with a recent American Academy of Neurology review of postherpetic neuralgia treatments. That study was led by Richard M. Dubinsky, MD, MPH, of the University of Kansas Medical Center.

"There are many treatments that work quite well and are well tolerated," Dubinsky tells WebMD. "The best are the tricyclic antidepressants, followed by opioids. Some people benefit from the lidocaine patch or capsaicin."

What should a patient try first? Dubinsky says that treatment must be individualized, and that a doctor's advice -- early on -- is crucial. The most important first step, he says, is to find out what drugs a patient is able to take. That decision is based on the patient's health, other current medications, and the side effects a patient has from certain drugs.

"If there are no contraindications, and the pain is debilitating, I would start a patient with tricyclic antidepressants," Dubinsky says. "If the pain is not that debilitating, I would try the lidocaine patch first. And if there is a contraindication to tricyclic antidepressants, I would go with opioids. This decision has a lot to do with what patients can tolerate."

If these individual medications don't work, Dubinsky would try a combination of tricyclic antidepressants and opioids. Such powerful combinations have powerful side effects, and he warns patients and doctors to plan for them in advance.

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By Daniel J. DeNoon, reviewed by Michael W. Smith, MD

SOURCES: Hempenstall, K. PloS Medicine, July 2005; vol 2: pp e164. Dubinsky, R.M. Neurology, September 2004; vol 63: pp 959-965. Andrew S.C. Rice, MD, reader in pain research, Imperial College, London. Richard M. Dubinsky, MD, MPH, associate professor, University of Kansas Medical Center.