On a lark, Dr. Andrea Boon decided to try some Botox a few years ago.

She expected the wrinkle above her nose to disappear.

And then, to her surprise, so did her migraines.

Boon, a physician at the Mayo Clinic in Rochester, Minn., became so intrigued that she started reading up on Botox, the injectable drug best known as a wrinkle remover.

And now she's leading a study to find out if it may help people with knee pain from arthritis.

To many people, Botox is just a vanity drug. But doctors say it also has potential as a powerful medicine because of the way it affects muscles and nerve endings. Made from the toxin that causes botulism, a form of food poisoning, Botox temporarily paralyzes and relaxes muscles under the skin.

There's also some evidence that it may interfere with the nerve signals associated with pain, says Boon.

As a result, doctors around the country have been trying it on a wide variety of conditions, from cerebral palsy to head and neck pain.

"People have seen anecdotally that it seems to work in pain," Boon said.

"So we wanted to study that to see if there's any scientific merit."

While the research has been sketchy, she said, the pain relief appears to last three to six months, about the same as the wrinkle relief.

Boon said she has tried Botox in patients with facial or neck and shoulder pain, and "it seems to work well."

Julie Schletty, of Dodge Center, Minn., was one of those patients. Diagnosed with fibromyalgia, she went to Boon because of "intense pain and discomfort" in her neck and shoulders. She got her first Botox injections about a year ago.

"I had the best six months that I've had in years," she said. Schletty, a 52-year-old engineer, said she was skeptical at first. But "when you're experiencing pain and discomfort chronically, you kind of are willing to look for other alternatives." Now the pain and stiffness have returned, she said, and she'll go back to Mayo next week for another Botox treatment.

Boon, a specialist in the department of physical medicine and rehabilitation, said she was especially intrigued with the idea that it might help patients with arthritis, who often suffer chronic pain in their joints. She was inspired, in part, by a small study at the University of Minnesota and Minneapolis Veterans Medical Center two years ago, showing that Botox appeared to reduce pain in a handful of people with arthritis. The research is ongoing at the veteran's hospital.