Most of us weathered childhood chickenpox years ago with no worse than some intense itching and a few missed days of school. But for approximately one out of three people who’ve had chickenpox—99 percent of us, according to the U.S. Department of Health and Human Services’ Centers for Disease Control and Prevention—that’s not the end of it. A painful viral infection called shingles can show up years later.

“It’s pretty common. About 30 percent of Americans will get shingles at some time in their lifetime; it turns out to be one million cases a year,” says Dr. Michael Walts, a family medicine physician with Alegent Creighton Health. “Usually shingles only occurs once. In most cases, it’s self-limiting; it goes away, and you don’t have any further problems.”

Shingles is so common because it’s caused by the varicella-zoster virus, the same virus that causes chickenpox, he explains.

“Although the [chickenpox] rash goes away, the virus doesn’t. It crawls into your spinal column, where it goes to sleep, maybe forever,” Walts says. “But maybe, for most reasons we don’t know, the virus wakes up and will crawl down one nerve of the spinal cord and into the skin. Wherever that nerve is going to, that’s where the shingles rash will show up.”

And unlike chickenpox, this rash is more than just annoying.

"The most significant risk factor for the development of shingles is age. The reason we think that’s the case is that the immune system, like everything else as we get older, just doesn’t work as well." - Michael Walts, M.D., family medicine physician with Alegent Creighton Health

“You’ll have pain first, and then all of a sudden the rash appears...It can be excruciatingly painful,” Walts says. And for some, the pain is long-lasting, even permanent.

“One of the most significant complications of shingles, a small percentage of time, is that even after the rash goes away, the pain doesn’t,” Walts explains. “The condition is called postherpetic neuralgia, or PHN.”

Shingles is more common after age 60, Walts says. “The most significant risk factor for the development of shingles is age. The reason we think that’s the case is that the immune system, like everything else as we get older, just doesn’t work as well. And the older you are when you get shingles—if you do—the more likely you are to get postherpetic neuralgia.”

It’s even possible that people who’ve been immunized against chickenpox can still get shingles later, he says, and it also strikes people who believe they’ve never had the chickenpox.

“People will say ‘I got shingles, but I never had chickenpox as a kid,’ and my response to that is, ‘Yeah, you did. You just didn’t know it,’” Walts says. “Maybe you had a bump or two that nobody ever even noticed, or maybe you had a rash that somebody said was contact dermatitis, because there’s no way you can get shingles unless that virus is living in your spinal cord.”

It’s not all bad news. A single-dose vaccine called Zostavax may prevent shingles altogether or prevent a recurrence. And if a person suspects shingles, especially when a rash appears on only one side of the body, he or she can still see their physician for treatment.

“(Anti-viral) medication does help. It does speed up the resolution of the pain and the rash, so go to your doctor and make sure it’s shingles,” Walts says. “We’re not sure about this, but one of the theories is that maybe treatment will not only decrease the amount of time you’re symptomatic, but it might decrease your risk for that postherpetic neuralgia. That’s all the more reason to get treatment, because, boy, anything you can do to prevent that side effect—even though it’s not common—you ought to try.”