The modern pharmacy is big and busy. Hundreds of prescriptions are filled daily in a typical chain drugstore.
Everyone is in a hurry. Pharmacists and technicians work at maximum speed, with limited time for lunch or bathroom breaks. Drive-thru windows give many drugstores the look and feel of a fast-food restaurant.
Patients behave the same way. They are eager to grab their bag of pills and dash out the door. That could be a prescription for trouble.
This experience was relayed to us: "I opened a new bottle of pills and saw the description written on the label — color of tablet, shape and code. I had seen that before but had not paid much attention to it.
"This time I checked the tablets and discovered that the bottle contained the wrong medicine. The color and shape were right, but the tablets were stamped with the wrong code.
"I returned to the pharmacy, where the pharmacist checked the medicine and said it was indeed the wrong pill. I had been given the correct medicine, but it was one that was four times as strong as my doctor prescribed. As a result, I resolved to check all medicines. Anyone can make a mistake, but I don't want to suffer the consequences."
This patient was wise to scrutinize his prescription bottle carefully. Many patients don't take the time. They just start swallowing pills.
With so many medications now available as generics, the shape and color of pills may not be a reliable guide to whether you have received the correct medicine. Pharmacies frequently change manufacturers, so tablets may have a different appearance from one refill to the next.
Had this patient unwittingly taken the quadruple dose that was dispensed, it is entirely possible that he would have suffered serious side effects.
Another reader reported a different kind of pharmacy error: "About 15 years ago, my son picked up a refill for his seizure medication. He started taking it as usual even though he noticed a minor change in the pill.
"He called me a few days later and said he wasn't feeling well. I told him to bring his meds so we could look them up in my reference book. Checking the pill in the image section showed that my son had been given a diuretic called Lasix in place of the three-times-a-day anticonvulsant medication he should have been taking.
"I rushed him to the emergency department, where they gave him IV potassium. The doctor told me if my son had let this go another 24 hours, his heart would have stopped and my son would have died.
"I now always check any new meds online. We have to be our own best advocate."
This important point is underscored by research showing that dispensing errors are common in hospitals and nursing homes as well as in community drugstores (Journal of the American Pharmacists Association, March-April 2009).
Because millions of mistakes occur every year, nobody can afford to be complacent about double-checking prescription medicines.
48%: Percentage of Americans took at least one prescription drug in the past month, according to the Centers for Disease Control and Prevention.
In their column, Joe and Teresa Graedon answer letters from readers. Send questions to them via peoplespharmacy.com.
Double-check your pharmacist's work
Prescription (The Image Bank, Getty Images)