text: prescriptions? why does rx mean prescription? "rx" and "medical prescription" are sometimes used interchangeably. the use of rx in prescriptions originated as an astrological symbol that was written for talismanic reasons at the start of medical prescriptions. later it changed into ℞ (an uppercase r with its tail crossed), and was used as an abbreviation for the latin word recipe = "take" (imperative), i.e. an instruction to the pharmacist to take the items listed in order to prepare the medicine. when printing came, it was rendered as "rx".