CHICAGO — Drug overdose deaths rose for the 11th straight year in 2010, federal data show, and most of them were accidents involving addictive painkillers despite growing attention to risks from these medicines.

"The big picture is that this is a big problem that has gotten much worse quickly," said Dr. Thomas Frieden, head of the Centers for Disease Control and Prevention, which gathered and analyzed the data.

In 2010, the CDC reported, there were 38,329 drug overdose deaths nationwide. Medicines, mostly prescription drugs, were involved in nearly 60 percent of the deaths, overshadowing deaths from illicit narcotics.

The figures for 2010 are the latest available nationally. The report appears in the Journal of the American Medical Association.

It details which drugs were at play in most of the fatalities. As in recent years, opioid drugs — which include OxyContin and Vicodin — were the biggest problem, contributing to three out of four medication overdose deaths.

Frieden said that many doctors and patients don't realize how addictive these drugs can be, and that they're too often prescribed for pain that can be managed with less risky drugs.

They're useful for cancer, "but if you've got terrible back pain or terrible migraines," using these addictive drugs can be dangerous, he said.

Medication-related deaths accounted for 22,134 of the drug overdose deaths in 2010.

Antianxiety drugs including Valium were among common causes of medication-related deaths, involved in almost 30 percent of them. Among the medication-related deaths, 17 percent were suicides.

The report's data came from death certificates, which aren't always clear on whether a death was a suicide or a tragic attempt at getting high. But it does seem like most serious painkiller overdoses were accidental, said Dr. Rich Zane, chairman of emergency medicine at the University of Colorado School of Medicine.

The findings are no surprise, he said. "The results are consistent with what we experience" in emergency rooms, he said, adding that the statistics no doubt have gotten worse since 2010.