<P> "Sell by date" is a less ambiguous term for what is often referred to as an "expiration date". Most food is still edible after the expiration date . A product that has passed its shelf life might still be safe, but quality is no longer guaranteed . In most food stores, waste is minimized by using stock rotation, which involves moving products with the earliest sell by date from the warehouse to the sales area, and then to the front of the shelf, so that most shoppers will pick them up first and thus they are likely to be sold before the end of their shelf life . This is important, as consumers enjoy fresher goods, and furthermore some stores can be fined for selling out of date products; most if not all would have to mark such products down as wasted, resulting in a financial loss . </P> <P> The expiration date of pharmaceuticals specifies the date the manufacturer guarantees the full potency and safety of a drug . Most medications continue to be effective and safe for a time after the expiration date . A rare exception is a case of renal tubular acidosis purportedly caused by expired tetracycline . A study conducted by the U.S. Food and Drug Administration covered over 100 drugs, prescription and over-the - counter . The study showed that about 90% of them were safe and effective as long as 15 years past their expiration dates . Joel Davis, a former FDA expiration - date compliance chief, said that with a handful of exceptions - notably nitroglycerin, insulin and some liquid antibiotics - most expired drugs are probably effective . </P>

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