And most of those leftovers were lingering in people’s medicine cabinets. More than 90 percent of the study patients said they had received no instruction from their doctor or pharmacist on what to do with unused pills.

A drawback of the study is that the researchers had to depend on patients’ memory and trust them to report accurately.

But even so, it seems clear that leftover narcotics “(end) up just sitting in people’s medicine cabinets, and that’s a real danger,” Bates said. He noted that anyone with access to your medicine cabinet, from your teenage child to your plumber, could easily take the medication.

In general, narcotic painkillers should either be flushed down the toilet or mixed with something unappealing - like cat litter or coffee grounds - and thrown away. But it gets confusing, Bates said, because the advice varies according to the specific narcotic.

Federal guidelines on safe disposal of narcotics and other drugs are available online, here

The written information that comes with narcotic prescriptions should also give instructions on how to dispose of leftover pills. But if you’re in doubt, Bates said, ask your pharmacist.

“In general,” he added, “make sure you know what’s in your medicine cabinet, and be aware of who has access to it. And if you have to have (narcotics) on hand, make sure they are secure.”

SOURCE:  Journal of Urology, February 2011.