His Pain : Her Pain

JON LEVINE was just testing painkillers on people who’d had a wisdom tooth extracted, when he uncovered rather more than he’d bargained for. The women in his study group found that strong painkillers related to morphine, called kappa-opioids, were most effective at numbing pain. But the same drugs didn’t work for the men at all. “In fact, the doses used in the clinical trial made pain worse for men,” says Levine, a clinical neuroscientist from the University of California in San Francisco.

He was shocked. “The idea that a therapy that had been around for decades could affect women and men in such dramatically different ways was anathema,” he says. “It was such an incredible mindset in the field of pain, missing what had clearly gone on in front of their eyes for years.”