The MC1R (melanocortin-1 receptor) gene produces melanin in humans. A variant of this gene present in redheads may be responsible for an increased sensitivity to pain. Non-redheads may carry this variant nor is it 100% guaranteed that a redhead will have it.
Many people will encounter anesthesia for the first time in their everyday lives at the dentist’s office. Administering too much anesthesia can have serious consequences so dentists are hesitant to go above recommended guidelines. Someone with a heightened pain sensitivity will likely never want to set foot in a dental office again after single procedure requiring anesthesia. Postponing dental care will likely make the problem worse and cause even more pain down the road.
“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.”
This led to two studies. In 2004, research showed that people with red hair need 20 percent more general anesthesia than blonds and brunettes.
A 2005 study indicated that redheads are more sensitive to thermal pain and are more resistant to the effects of local anesthesia.