clipped from www.medscape.com

The military was sitting on a $1 billion stockpile of drugs and facing the daunting process of destroying and replacing its supply every 2 to 3 years, so it began a testing program to see if it could extend the life of its inventory. The testing, conducted by the US Food and Drug Administration (FDA), ultimately covered more than 100 drugs, prescription and over-the-counter. The results showed that about 90% of them were safe and effective as far as 15 years past their original expiration date.

"Manufacturers put expiration dates on for marketing, rather than scientific, reasons," said Mr. Flaherty, a pharmacist at the FDA until his retirement in 1999. "It's not profitable for them to have products on a shelf for 10 years. They want turnover."

The FDA cautioned there isn't enough evidence from the program, which is weighted toward drugs used during combat, to conclude most drugs in consumers' medicine cabinets are potent beyond the expiration date.