THROW AWAY old medicine? We know we should, but most of us can't bring ourselves to do it. If it looks OK, we'll keep it around, even after the expiration dates stamped on the bottles. Just in case.
Joseph Belson warns that consumers who assume that those old drugs are still safe to use are taking a real chance.
"It's risky," Belson said recently. "People . . . take it for granted that fruit in the refrigerator will go bad. But they seem to think that drugs last forever."
Belson is a drug scientist with the United States Pharmacopoeia Convention Inc. (USP), the organization that sets standards for drug strength, quality, purity, packaging and labeling.
Prescription drugs and over-the-counter medicines can and do go bad, sometimes in just days or weeks, he said. And they may go bad quickest if they are kept, of all places, in your medicine cabinet.
"The major thing is just that it will degrade, and it will not be effective," Belson said. But for some drugs, the chemicals formed as the medicine degrades "can be more dangerous than the drug itself."
The antibiotic tetracycline, for example, breaks down into 4-epianhydrotetracycline, which is considered toxic, he said. The USP urges that any outdated or decomposed tetracycline be discarded.
You can't just rely on the expiration date on the bottle, Belson said. Here's why:
Under U.S. law, it's up to the drug manufacturer to set the expiration date after a test of the product's chemical stability over time. At some point during the test, either the drug starts to go bad or the company decides it has remained stable for as long as it's likely to remain on anyone's shelf.
So they end the test and set an expiration period they're willing to guarantee -- usually two to five years after the date it was made, Belson said.
But the tests are conducted with the drugs sealed in the manufacturer's container.
"The expiration date means that if you don't open the [original] container, the manufacturer guarantees it [the medicine] will last until that day," Belson said. "After this date, you're on your own."
"In reality," he said, "some products could last much longer. Very few drugs will be great to the end of November, and then on Dec. 1 go to zero. But they do degrade."
The real trouble for consumers comes after the manufacturer's original container has been opened. Once your pharmacist opens the original container, the drug's clock speeds up, and runs down faster.
Medicine repackaged by your pharmacist into one of those familiar brown plastic vials must be labeled with an expiration "no more than one year" from the date it was repackaged, regardless of the manufacturer's expiration date.
If it was repacked into single-tablet "unit-dose" envelopes, the drug expires in six months or less. And those reconstituted antibiotics parents mix up for their kids are good for 30 days if they're refrigerated, and just seven days if they're not.
The villain here is usually moisture, with light and heat playing strong supporting roles. Some brands break down faster than others, too.
"Moisture is the No. 1 killer" of medicines, Belson said. "And if you stop and think of where most people store their drugs, it's in the bathroom where it gets steamed regularly. And it's probably one of the warmest rooms in the house. Or [they keep drugs] in the kitchen, probably the next-steamiest."
If expiration dates aren't always reliable, how should consumers deal with aging medications?
"People who use medications regularly in their family should become familiar with the normal appearance, and the normal odor" of their pharmaceuticals, and examine them for signs that they have begun to deteriorate, Belson said.
While the medications are still fresh, they should not be stored in the bathroom, or any other, warm, moist, brightly lighted place.
The best place for medications you won't need often, he said, may be in a dry basement, where it's "cool and usually dark."
Otherwise, the best spot may be a bedroom drawer well out of children's reach.