If you’ve ever walked out of a doctor’s appointment with a prescription or two in your hand, there’s a good chance that you couldn’t begin to decipher what exactly was written on the paper in front of you. In fact, this inability to decipher may have had nothing to do with the poor penmanship that people say is so rampant in the medical profession, but rather with the series of numbers and seemingly random abbreviations.

While this veritable alphabet soup may seem as if it serves no purpose, this is not actually the case. The abbreviations in questions are actually shorthand for Latin phrases that have existed in the medical field for thousands of years.

For instance, the abbreviation “q.d.” stands for quaque die, meaning every day, while the abbreviation “b.i.d.” stands for bis in die, meaning twice per day, and the abbreviation “NPO” stand for nil per os, meaning nothing by mouth.

While this seemingly secret Latin code may sound interesting on its face, some safety experts theorize that it may actually create an elevated risk of harm to a patient in the form of possible medication errors.

That’s because a pharmacy staff member who is perhaps not well trained or simply inexperienced may become confused by this Latin shorthand and make what proves to be a serious mistake.

An example given by safety experts is the abbreviation “h.s.,” which stands for the Latin phrase hora somni. Translated to English, this simply means to be taken at bedtime. Here, say experts, it’s conceivable how an inattentive staff member could simply read h.s. as half strength, meaning the patient would either get the wrong dosage or the wrong instructions.

The safety experts concede, however, that getting physicians to move away from this arcane shorthand may be easier said than done as the practice in so engrained in the profession. In the meantime, however, they advise patients to always read both the prescription bottle and the attached instructions, and to ask as many questions as they want if something looks wrong.

Source: The Tampa Tribune, “Doctor’s cling to confusing secret code,” Joe Graedon and Teresa Graedon, April 12, 2014