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NIH News in Health, June 2005

Red Hair Blues

Some doctors have claimed that people with naturally red hair may need more anesthetic than others. It turns out they may be right.

Dr. Daniel Sessler of the University of Louisville School of Medicine decided it was time to put the issue to the test. His research group, with funds from NIH, recruited 10 women with naturally bright red hair and an equal number with black or dark brown hair.

Researchers gave the women an inhaled anesthetic, then applied a harmless shock to each woman’s thigh and watched for movement. They adjusted each woman’s dose until she had a reflex movement half the time, a standard method for finding the right dose of an anesthetic. Nearly all of the red-haired women needed 20 percent more anesthetic than those with dark hair.

Just about all people with red hair share a common genetic variation that affects hair and skin color. After analyzing DNA from the women, the researchers identified this variation in 90 percent of the red-haired women who needed more anesthetic.

While these findings don’t directly link hair color genes to anesthetic response, they do suggest that health care providers should monitor anesthetic doses carefully in redheads. The research also opens the door to further study into the genetics of anesthetic response.

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