N ine distinct pains have plagued Terrie Cowley since the summer of 1982.

One, bone pain, “is like a glass of ice. When you pour in water, you hear that cracking. That’s how my skull sometimes feels—intense, streaking pain.”

Two, “chemical” headaches. “It’s that horrible feeling as if you’ve had too much wine and you can barely pick your head up off the pillow.”

Three, brush-burn pain. “If you wash your face, the slightest touch stings and burns—you feel like roadkill.”

Four hits the lymph nodes, five the eyes, and six the throat. “You swallow and feel as though your eyeballs were going down your throat,” Cowley says. Tooth pain, burning mouth and deep-muscle pain fill out the list.

Cowley had felt none of this before her jaw surgery, and she wondered what could have gone so terribly wrong. Immediately following the procedure to correct a clicking and popping condition in her jaw called temporomandibular joint disorder (TMJD), she asked her oral surgeon whether she had fallen off the gurney while she was unconscious. It wasn’t just her head; her entire body ached and throbbed, as if she had a severe case of the flu.

Two months later, when the pain had not subsided, she asked whether he had cut her brain accidentally. Or whether she was going to die. When he told her there was nothing wrong with her, she went home and shut up because she didn’t want to become grist for the rumor mill in the hospital, where her husband worked.

Cowley suffered silently for four years. But in 1986 she met a kindred spirit—a woman who experienced similar pain, though she had never had surgery. The two sponsored a meeting to see whether anyone else felt the same way. One hundred twenty people showed up. It was the beginning of a support group that now assists TMJD patients worldwide.

One in 10 Americans suffers chronic pain that lasts at least a year, a ratio that rises to six in 10 for those older than 65. Pain underlies 20% of doctor visits and 10% of all prescriptions written, even though, for many chronic-pain sufferers, drugs don’t do much. Some of the most effective medicines are hardly cutting edge: Opiates, including morphine, have been in use for hundreds of years, as has the willow bark from which aspirin is derived. Newer medications such as anticonvulsants and antidepressants sometimes help, but they often leave patients feeling drugged.

“I think it is the norm, not the exception, that pain is not completely resolved,” says neuroscientist Jon-Kar Zubieta of the University of Michigan in Ann Arbor. “None of the currently available drugs is very effective,” says Massachusetts General Hospital neuroscientist Clifford Woolf. “You typically need to treat four to 10 patients to get one who responds well.”

But a growing understanding of the nature of pain could soon provide better options. Research into what goes on in the body during chronic pain is beginning to generate ideas for drugs and other treatments, stirred by a new focus on genetics. Gene studies reveal that everyone’s experience of pain is different, and that roughly half of our sensitivity to pain is determined by our genetic makeup. Some people are much more prone than others to develop chronic pain after surgery; to suffer, without surgery, from fibromyalgia and TMJD; or to feel more pain when pricked or punched.

“We used to think reaction to pain was largely culturally determined—with stoic Northerners and hysterical Mediterraneans,” says Woolf. “In fact, how one feels pain turns out to be in good part a matter of genetics. This understanding has given us a totally new perspective, and if we can target pain’s underlying mechanisms, we can prevent changes that lead to chronic pain. I think we’re on the cusp of a total revolution in our approach to pain.”

Though doctors have hundreds of ways to catalogue pain, Woolf sticks to four categories. Nociceptive pain is the feeling that makes you pull your hand away from a hot casserole dish or sharp knife, a response essential to survival. A recent report in the journal Nature tells of individuals from three families in Pakistan who can’t feel any type of pain at all. One, a boy well-known for his street theater—stabbing knives through his arms and walking on burning coals—jumped to his death from a roof on his 14th birthday.

Inflammatory pain is next. Think of a swollen toe that throbs at the slightest touch, the sunburn that can’t stand the shower. This too is a form of protection, encouraging us to remain immobilized as we heal (though some disorders, such as rheumatoid arthritis, occur when this process continues for no healthy reason). Inflammatory pain is alleviated by drugs like aspirin, ibuprofen and acetaminophen, whereas morphine and stronger narcotics allay nociceptive pain during and after surgery.