The Journal of the American Medical Association and the U.S. Centers for Disease Control published a report this week estimating that as many as 700,000 Americans wind up in the emergency room every year due to adverse reactions produced by combining prescription drugs with over the counter drugs or herbal supplements. Most of the affect population is over 65. The projection is based on a surveillance project on outpatient drug safety that started in 2004.

The Chicago Tribune reports that

The study’s authors said that in 2004, 82 percent of the U.S. population reported using at least one prescription drug, over-the-counter medication or dietary supplement, and 30 percent reported using five or more drugs. More effort must be made to prevent adverse events, the researchers said.

The study’s database included 63 nationally representative hospitals that reported 21,298 adverse drug reactions among American adults and children treated in emergency rooms during the two-year period.