Famous author Mark Twain wrote, in 1864, that doctors should "discard abbreviations… to avoid the possibility of mistakes." We agree! A prescription for medicine should not be a mystery to understand. Many abbreviations and words in prescriptions come from Latin. We'd like to help by explaining each part of a typical prescription and translating some of the Latin abbreviations into English words.
Download: Learn to read your prescription
Rollover letters A-K to for an explanation of each part of a prescription.
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| Common abbreviation | Latin words that make up the abbreviation | The meaning on your prescription |
|---|---|---|
| ac | ante cibum | before meals |
| bid | bis in die | twice a day |
| gtt | gutta | drop (as in 1 drop, 2 drops, and so on) |
| hs | hora somni | at bedtime |
| od* | oculus dexter | right eye |
| os | oculus sinister | left eye |
| po | per os | by mouth |
| pc | post cibum | after meals |
| prn | pro re nata | as needed |
| qd** | quaque die | every day, or daily |
| qid | quarter in die | 4 times a day |
| tid | ter in die | 3 times a day |
*Sometimes, od is used to mean "once daily." The word "daily" should be used instead to prevent mistakes.
**The abbreviation qd is considered dangerous. It should not be used because it has been mistaken as qid frequently. This mistake has led to serious harm, since people took once-a-day medicine four times each day.