New research published in this month’s Journal of American Dental Association found that painful experiences at the dentist might cause more anxiety for men and women with red hair, who were twice as likely to avoid dental care than people with dark hair.

“Redheads are sensitive to pain,” said Dr. Daniel Sessler, an Outcomes Research Department chair at The Cleveland Clinic, in Cleveland, Ohio, who is one of the authors.

“They require more generalized anesthesia, localized anesthesia. The conventional doses fail. They have bad experiences at the dentist and because of the bad experiences, they could avoid dental care.”

Sessler, an anesthesiologist, began studying redheads’ sensitivity to pain after hearing chatter from colleagues.

“The persistent rumor in the anesthesia community was that redheads were difficult to anesthetize,” Sessler said. “They didn’t go under, had a lot of pain, didn’t respond well to anesthesia. Urban legends usually don’t start studies, but it was such an intriguing observation.”