All drugs have side-effects and also have the potential for causing an adverse reaction. According to research published in the Journal of the American Medical Association (Vol. 296 No. 15, October 18, 2006), over 700,000 Americans end up in the emergency room each year due to reactions to prescription medication. The most common causes are allergic reactions and accidental overdoses.

According to the authors of the study and other experts, this number may actually be low because drug reactions are often misdiagnosed. Patients aged 65 and over are twice as likely to suffer from an adverse drug reaction as a younger person.

The results are from 2004-05, and are from the first two years of data from a national surveillance project on outpatient drug safety. The project was developed by the federal Centers for Disease Control and Prevention, the Food and Drug Administration and the U.S. Consumer Product Safety Commission. Americans use more prescription medication than any other people in the world. The CDC estimates that about 130 million Americans use prescription medications each month.