Med Abbreviations #2

Rx
  It refers to a prescription. It's latin for 'Recipe'

I prefer the explanation that Rx is derived from the astrological sign for Jupiter which was once placed on prescriptions to invoke that god's blessing on the drug to help the patient recover.

It isn't really Rx, though that's as close as we get with normal fonts: it's an R with a slash through the tail. And it's short for the Latin "recipe." Recipe is the imperative form of the verb "to take," and is usually translated as "take thou." It's an instruction to the pharmacist about the ingredients to compound a prescription, just as a recipe for cooking lists its ingredients. Of course, pharmacists rarely compound prescriptions any more, but the tradition continues.

The origin is debatable. John de Witt's answer is commonly accepted. But here is a second opinion: theory number two, from the book Devils, Drugs, and Doctors, written in 1931: "Rx is not, as is frequently supposed, an abbreviation of a Latin word meaning recipe or compound, but is an invocation to Jupiter, a prayer for his aid to make the treatment effective...sometimes in old medical manuscripts all the R's occurring in the text were crossed." In other words, the Rx symbol was a corruption of the ancient symbol for the Roman god Jupiter. If you're an astrology fan, you know this symbol which has a very similar crossed leg at the bottom right.




SOS
It means "repeat once if urgent"...I know it doesn't make sense, but many medical abbreviations don't - a lot are based on the Latin and/or Greek origin of the word.


S.O.S. [L.] si o´pus sit (if it is necessary)