Do you follow all of your doctor's orders when it comes to taking prescribed medications? If you're like most people, the answer is "no."

On average, Americans 40 and older with a chronic medical condition get only a C+ in proper medication adherence, according to a survey from the National Community Pharmacists Association. One-third of respondents received a D or an F. Only 24 percent said they did everything correctly and got an A.

advertisement | advertise on newsday

The grades were based on several categories: failing to fill or refill a prescription, missing a dose or taking a higher or lower dose, taking an old medication for a new problem without consulting a doctor, taking someone else's medicine, stopping a prescription early and forgetting to take a medication.

The pharmacists association noted that taking medications improperly not only potentially harms patients, it adds an estimated $290 billion a year in health care costs.