See How Drugs Get Mixed Up at Pharmacies

Abbreviations can also cause mix-ups. The abbreviation "PTU," as seen on this handwritten prescription, is used for both purinethol, a leukemia drug, and propylthiouracil, a drug used to treat hyperthyroidism. The duplication has been the source of a number of serious medication errors, according to the Institute for Safe Medication Practices, a non-profit advocacy group that monitors medical errors. In 2008, the Institute for Safe Medication Practices received a report of a pregnant woman who was mistakenly dispensed purinethol instead of propylthiouracil. After taking the wrong drug for weeks, the woman eventually lost her baby and died. (Institute for Safe Medication Practices)