July 25, 2005 -- 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% to 15% 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."
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:
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.