Medication errors may be more common than you think. One study by the Institute of Medicine found that medication errors harm about 1.5 million people a year in the United States and claim several thousand lives. One large scale study of 36 hospitals reported that drug-related errors occur in one out of every five doses given to patients.

There are many types of medication-related errors that are possible.

The National Academies of Science (NAS) has broken down medication errors into categories according to where they occurred. The NAS estimates that nearly 400,000 preventable drug-related injuries occur in hospitals each year, while 800,000 occur in long-term care facilities and 530,000 occur just among Medicare recipients in outpatient clinics.

In addition to the physical harm they cause, the staggering financial impact of medication errors is believed to be in the neighborhood of $4.4 billion in extra medical costs every year.