FRIDAY, Dec. 2 (HealthDay News) -- Prescriptions for opioid painkillers to treat chronic abdominal pain more than doubled in the United States between 1997 and 2008, according to a new study.

This large increase of prescriptions written at outpatient clinics is concerning for several reasons, said lead author Dr. Spencer Dorn, an assistant professor of medicine at the University of North Carolina Medical School at Chapel Hill, and colleagues.

Very little evidence exists to support the use of opioids to treat chronic pain that isn't cancer related, and opioids are frequently misused and sometimes abused, Dorn said. Extended use of opioids can trigger other gastrointestinal symptoms such as nausea, vomiting and constipation, and may even worsen abdominal pain, he added.

The study appears in the December issue of the journal Clinical Gastroenterology and Hepatology.

Chronic abdominal pain is a common problem but is often incurable, which can make it challenging for doctors to help patients, the researchers said.

"Writing a prescription for a painkiller may be the path of least resistance; doing so may satisfy the patient's demand for relief and mitigate the clinician's possible feelings of inadequacy," Dorn said in a journal news release.

Numerous factors have likely contributed to the sharp rise in the use of opioids to treat chronic abdominal pain, the researchers said. These include a tendency to generalize recommendations for opioids' use in treating pain and widespread direct-to-consumer advertising.

More information

The American College of Gastroenterology has more about abdominal pain.