The Food and Drug Administration (FDA) has operated an adverse drug warning system since 1998. From 1998 to 2005, the incidence of serious adverse reactions to prescription drugs increased from 35,000 to 90,000 per year and deaths increased from 5500 to 15,000. During this period, the incidence of adverse events increased 4X more than the number of prescriptions increased. These statistics were reported in the Sept 2007 issue of the Archives of Internal Medicine and are now posted on the FDA web site. Drugs are getting more and more dangerous, as well as more expensive. Natural alternatives make a lot more sense when they are effective, which is frequently.
See the FDA web site.