Shingles is the grown-up version of chickenpox, affecting people who had the itchy-scratchy virus as a kid—which is about 99.5 percent of Americans over 40.  Shingles usually manifests as pain, itching or tingling that starts on one side of your face or body, then turns into a nasty rash, at times accompanied by fever, headaches, upset stomach and nerve pain. Shingles has been on the rise since the 1990s—there are about a million cases in the U.S. every year—and while doctors don’t know why, they’re sure it’s not related to prevalence of the chickenpox vaccine, as one common theory suggests.

READ MORE: Should You Get the Shingles Vaccine?