The Grammarphobia Blog

The right medicine

Q: Why is the paper from a doctor that is filled at a pharmacy written “prescription” but pronounced “perscription”?

A: The thing your doctor writes should be pronounced “prih-SKRIP-shun.” The vowel in the first syllable sounds like the “i” in “rib,” and it follows the “r” sound. Anyone who says the first syllable as “per” is mispronouncing the word.

This transposing of consonant and vowel sounds is called metathesis. (That’s pronounced muh-TA-thuh-sus.) Other examples include transpositions like hunderd (for “hundred”), modren (“modern”), interduce (“introduce”), prespiration (“perspiration”), and purty (“pretty”).

When “prescription” entered English in the early 1400s, it referred to the use or possession of something for a long period of time or to the legal right to it because of such use or possession.

The word didn’t appear in a medical sense until the mid-1500s. The first published reference for this usage in the OED is from Gilbert Skeyne’s Ane Breve Description of the Pest (1568). The book, which describes an outbreak of the Black Death in Edinburgh, is said to be the earliest Scottish medical text.

By the way, the term “Rx” is an alteration of the medical symbol for a prescription (a capital “R” with a cross on the diagonal leg).

Some people have speculated that the medical symbol is derived from various ancient symbols, but the OED has a more prosaic explanation: it comes from the first letter of the Latin imperative recipe, or “take,” as in “Take one amoxicillin capsule every eight hours.”

The dictionary’s first citation for the medical symbol (the capital “R” with a cross) is from a 1559 translation of a Latin work on distilling medicine from plants.

The first citation for the letters “r” and “x” used together in place of the medical symbol is from an 1855 article in the New Hampshire Journal of Medicine: “The following prescription was most useful. Rx Valerian Fl. Ext.”

The earliest published reference for the two letters used in an everyday way simply to describe a prescription ordered by a doctor is from a 1911 ad in a Syracuse, NY, newspaper that mentions “RX prescription shoes.”

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