Chronic pain is a common and difficult problem. The 2012 National Health Interview Survey showed that nearly 40 million U.S. adults (17.6 percent) have severe pain and about 25.3 million (11.2 percent) have pain every day. The annual economic cost of chronic pain in the United States, including both treatment and lost productivity, has been estimated at nearly $635 billion. To manage pain, many patients are prescribed drugs such as opioids, but the drugs aren't consistently effective, can have disabling side effects, may worsen pain conditions in some people, and can be misused. There's evidence that some complementary health approaches may help people manage pain, and they might also enable people to reduce their use of pain medications.