Generic drugs are used for more than 70 percent of prescription medications Americans take every year. They're popular because they're less expensive than brand names, but a new study found that many people don't take them as prescribed.

Mort Allen, 73, takes medication for hypertension, elevated cholesterol and diabetes. Managing all three can be confusing, he says.

"This one drug, it's either blue or white," Allen says. "It changes colors and so you don't really know."

A Brigham and Women's Hospital study recently found that when generic pills look different than brand name ones, patients are 50 percent more likely to stop taking them.

Doctors caution pharmacy customers, though: Even though generic medications look different, they are still the same drug.

"During consult, we'll tell them there's a difference in shape and size," said pharmacist Dr. Ike. "In addition, we put a little sticker on the bottle saying the same exact information."

Patients should talk to their doctor or pharmacist if they have any questions.