Recently, a friend had a doctor’s appointment. During the visit, the doctor told him that his cholesterol levels were low enough that he could stop taking Lipitor, the cholesterol-lowering statin drug.

Great news, he thought.

But the next time he visited his pharmacy to pick up his allergy medication, my friend was surprised and confused when, along with the allergy drug, his pharmacist handed him his usual refill of Lipitor.

He wondered…

Did my doctor neglect to tell my pharmacist that I’m not supposed to take this drug anymore?

Or did my doctor change his mind, decide that I should stay on Lipitor and neglect to tell me?

Because my friend was alert during his pharmacy visit, he called his doctor on the spot and also talked with his pharmacist to get to the bottom of it. And it’s a good thing that he did—because the doctor had not communicated the change to the pharmacist, and my friend did not need the Lipitor.

But his story has me worried. For instance, suppose there are elderly patients who may not be as mentally sharp as they used to be and who are accustomed to picking up, say, four or five medications at once from the pharmacy. In a situation like my friend’s, would such patients have simply kept on taking unneeded medications?

DON’T MAKE ANY ASSUMPTIONS

Communication lapses between doctors and pharmacists—and between those medical professionals and patients—occur more often than you might think, according to a new study from Brigham and Women’s Hospital and Harvard Vanguard Medical Associates, a medical group practice in Boston. The consequences of those lapses can be significant.

In fact, the study researchers found that about 1.5% of all discontinued prescriptions were nonetheless refilled by pharmacies. Even worse, 12% of those errors caused potential harm to the patients. In some cases, the harm consisted of mild side effects such as nausea or lightheadedness…but in other cases, the harm involved potentially serious problems such as low blood pressure or allergic reactions.

The moral of the story: Never make any assumptions when it comes to your prescriptions—and that includes stopping old drugs as well as starting new ones. Physicians and pharmacists are human and sometimes make mistakes. For instance, your doctor might flat out forget to pass along the message to your pharmacy or assume that you will tell your pharmacist to stop refilling the prescription. Or, as the study revealed, the doctor might enter the medication halt into your electronic health record, supposing that this information will be transmitted to the pharmacy—though in fact this does not automatically occur.

Safest: If your doctor tells you to stop taking a certain drug, before you leave his or her office, call your pharmacy to confirm the change. And if your pharmacist ever hands you a drug that your doctor told you to stop taking, don’t accept it without question. Instead, call your doctor that instant to clear things up before you pay for the drug—and certainly before you use any of it.