Redheads Are a Tough Knockout

A new study finds you're likely to need more anesthesia when you go under the knife than do people with other hair colors. Researchers at the University of Louisville discovered that, on average, people born with red hair require about 20 percent more anesthesia to obtain satisfactory sedation.

Dr. Edwin B. Liem, an anesthesiologist at Louisville's Outcomes Research Institute and the study's principal investigator, presented his results today at the American Society of Anesthesiologists annual meeting in Orlando, Fla.

Red hair, he discovered, may be a small detail that makes a big difference in terms of memory, pain and sedation in the operating room.

"A person who receives too little anesthesia may recall the surgery or may have actually have heightened pain during the procedure," Liem explains. "Neither of these are desirable outcomes. The art and science of anesthesiology is determining just the right amount of anesthesia to achieve unconsciousness, pain tolerance and suppression of memory without causing adverse consequences, such as cardiac or pulmonary complications. Red hair is apparently an important element in this decision."

According to Liem, the discovery is particularly noteworthy because red hair is the first visible human characteristic — or phenotype — to be linked to the amount of anesthetic needed in surgery. Although neither he nor anyone else knows exactly why this link exists, Liem says his best guess at the moment is that it's somehow related to what's known as the "dysfunctional melanocortin 1 receptor."

Scientists have known for a long time that melanocortin receptors on certain cells are responsible for hair and skin color. Liem believes a dysfunction of this receptor triggers an increase of the hormone that usually stimulates the cells. This happens to be the very same hormone that stimulates a receptor in the brain that governs pain sensitivity.

"Redheads are likely to experience more pain from most stimuli — surgery is just one example — and therefore require more anesthesia to alleviate that pain," Liem says.

Redheadedness has been linked to other medical anomalies or differences in the past.

Dr. Larrian Gillespie, a urologist and gynecologist in Beverly Hills, Calif., says there are a number of "redhead-related" disorders, as these are increasingly called.

In treating interstitial cystitis, for example, Gillespie has found black women are unlikely to have the condition — unless they have a naturally redheaded mother or grandmother.

"There are definitely different metabolic factors at work in redheads," she says. "I am not at all surprised to learn that redheads need more anesthesia than non-redheads. The red hair is more than a cosmetic characteristic; it is a biological marker, apparently for many other bodily processes."

Previous research has shown that redheads tend to have skin that is more sensitive to the sun and may have as much as five times the risk of melanoma, a skin cancer. And 2000 study suggested red hair may accumulate drugs at a different rate than hair of other colors, thus letting redheads pass drug tests more easily than brunettes.

The fact that they're not exactly like everyone else can have important implications for redheads, says Liem — especially redheads facing surgery.

"If I had red hair, I'd want to make sure my anesthesiologist is familiar with the fact that I'm very likely to need more anesthesia because of my hair color," he says. "Many anesthesiologists have already figured this out in practice and will give more anesthesia, but for those anesthesiologists that aren't aware, it would be a good idea to point this out."

Of equal importance, Liem notes, is that the research provides some of the strongest evidence to date that genetics plays a role in anesthetic requirements in humans.

"Despite more than a century of research and the fact that anesthesia is extraordinarily safe, we still are not at all certain about how anesthetic gases work," he admits. "Unraveling the link between red hair, the mutations at the melanocortin 1 receptor, and anesthetic requirements may be a first step toward understanding how inhalational anesthetics work."

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