After colds and flu, back pain ranks as the leading reason for days lost from work and school. Between medical care and lost productivity, back pain costs the nation about $ 24 billion a year.

But that figure may soon start to decline, as more and more people discover that a blended approach to treatment can heal their backs faster and often less expensively than the drugs-or-surgery route advocated by mainstream medicine.

The trouble starts in your spine, which consists of 33 doughnut-shaped bones called vertebrae that are stacked on top of each other to form the subtle S-curve of your spine. Sandwiched between most of the vertebrae are flexible cartilage disks, which provide cushioning.

The alternating bone-cartilage construction gives your spine remarkable flexibility. But unfortunately, that construction also invites injury. The most vulnerable area is your lower back.

Since most of your body weight lies in front of your spine, your vertebrae are constantly being pulled forward and out of alignment. Other factors can contribute to vertebral strain, including overweight, injury, and everyday wear and tear.

Vertebral misalignment is just one of several structural problems that may contribute to back pain. Structural problems are quite common, primarily because of the spine's complex construction. With so many different parts, a lot can go wrong with the disks, muscles, and nerves.

Until recently, experts believed that structural problems were the source of all back pain. Now they know that's not the case. In fact, a landmark 1994 study found that many people have significant vertebral misalignment, bulging disks, even ruptured disks-yet never experience back pain. Conversely, you may suddenly develop it for no apparent reason, and your doctor may be unable to determine what's behind it.

Among mainstream M.D.'s, there has been ongoing debate about the best ways to treat back pain. Until the 1990s, people with it routinely received "prescriptions" for extended bed rest and pain-relieving drugs-and quite often surgery. But research has shown that extended bed rest often makes it worse and that surgery is rarely necessary. Now most mainstream M.D.'s suggest a day or two of pain relievers and no more than 2 days of bed rest, followed by fairly speedy return to a normal level of activity.

With a conservative approach to treatment, about 90 percent of people with back pain feel significantly better within a few months, says former back-pain sufferer Louis Kuritzky, M.D., assistant professor of family medicine at the University of Florida in Gainesville. For the vast majority of people with back problems, once the pain is gone, it doesn't come back. About 15 percent of people develop chronic pain that persists or recurs for years.