The U.S. Food and Drug Administration began requiring prescription medication be labeled with expiration dates in 1979. Expired drugs account for 25 percent of annual health care costs in the U.S.
Analysis of 30-year-old medication demonstrates that up to 86 percent of the compounds remained potent, suggesting further testing may lead to longer expiration dates
The best and most effective way of reducing your health care costs, and the cost to the environment of discarded medication, is to reduce your dependence on drugs through lifestyle changes.
Here is link for the report.