Have you ever left the doctor’s office not remembering exactly which medication your doctor prescribed and later, whether the pharmacist got it right?

Names like Darvan and Diovan can sound the same. But one is a pain reliever while another is used to treat high blood pressure. And when a pharmacy gives one of the medications to a patient who really needs the other, it could lead to some serious consequences.

Anecdotal evidence suggests that this problem is more common than believed, especially because there are various ways to fill prescriptions, including in-store and online. But there’s no formal method used to track pharmacy errors, according to Dr. Carolyn Clancy, director of the Agency for Healthcare Research and Quality.

“There are a number of times I’ve asked patients about the types of medication and they’ll say it’s a small, white pill,” said Clancy.

Sean O’Connor, 16, of Meza, Ariz., who was prescribed pain medication following wisdom teeth extraction, found out he was given the wrong medication when he received a call from his pharmacist four days later.

The pharmacy that filled Sean’s prescription for pain medication gave him a chemotherapy drug to treat leukemia instead of the pain pills he needed.

“There was another guy at the pharmacy with my name … another Sean O’Connor, who apparently had cancer, I guess,” Sean told the ABC affiliate in Meza.

Sean had taken 17 pills of the leukemia drug before he was alerted about the mistake. While blood tests reveled that Sean had a higher-than-normal blood pressure, the drug he took can cause more serious side effects, including sterility.  

“I just think that would be sad, and I think it would be hard to get older and never have kids,” said Sean.

Besides medications that may sound or look alike, other factors can contribute to the wrong prescription getting filled.

Reading a doctor’s handwriting may be just as difficult for some pharmacists as it is for patients. And because some prescriptions are filled with the cheaper generic alternative of a prescribed brand name drug, it’s difficult for many patients to tell whether they’re receiving the correct substitute.

Most pharmacies don’t report prescription errors because they’re not required to. Neither the federal government nor  most states in the U.S.  have  laws requiring that drugstores report prescription errors, even if the cases lead to serious complications or death.

“Pharmacies consider even one prescription error to be one too many,” said Chrissy Kopple, a spokeswoman for the National Association of Chain Drug Stores. “Recognizing that human error is a possibility in any profession, pharmacies constantly pursue opportunities to improve safety.”

Scanning technology is used in some instances to verify that the medication that has been prescribed matches the medication that’s dispensed.  Also, the use of electronic prescribing is on the rise, which can potentially reduce the risk of errors from prescribers’ handwriting and from incorrectly entering prescription information. 

But until these technologies catch on, both pharmacists and patients should create their own checks and balances to make sure the right medication gets into the right hands, said Kopple.

The Agency for Healthcare Quality and Research offers a few tips that consumers can use to lower the chance of  pharmacy errors:

• When your doctor writes a prescription for you, make sure you can read it. 
• When you pick up your medicine from the pharmacy, ask the  pharmacist if this is the medicine that your doctor prescribed.
• Open the bag containing your medication container, and make sure the medicine matches your prescription and your name is on the container.
• Make sure you understand how to properly take the medication. Ask your pharmacist about how much medication to take, when and whether you should expect to experience any side effects.