The main discussion of these abbreviations in the context of drug prescriptions and other medical prescriptions is at List of abbreviations used in medical prescriptions . Some of these abbreviations are best not used, as marked and explained here.
| Abbrev. [1] | Meaning [1] | Latin (or Neo-Latin) origin [1] |
|---|---|---|
| a.c. | before meals | |
| a.d., ad, AD | right ear | auris dextra |
| a.m., am, AM | morning | ante meridiem |
| nocte | every night | Omne Nocte |
| a.s., as, AS | left ear | auris sinistra |
| a.u., au, AU | both ears together or each ear | aures unitas or auris uterque |
| b.d.s, bds, BDS | 2 times a day | bis die sumendum |
| b.i.d., bid, BID | twice a day / twice daily | bis in die |
| gtt., gtts | drop(s) | gutta(e) |
| h., h | hour | hora |
| qhs, h.s., hs | at bedtime or half strength | quaque hora somni |
| ii | two tablets | duos doses |
| iii | three tablets | trēs doses |
| n.p.o., npo, NPO | nothing by mouth / not by oral administration | nihil per os |
| o.d., od, OD | right eye once a day (United Kingdom) | oculus dexter omne in die |
| o.s., os, OS | left eye | oculus sinister |
| o.u., ou, OU | both eyes | oculus uterque |
| p.c. | after food | post cibum |
| p.m., pm, PM | afternoon or evening | post meridiem |
| p.o., po, PO | by mouth / oral administration | per os / nonstandard form per orem |
| p.r., pr, PR | rectally / rectal administration | per rectum |
| p.r.n., prn, PRN | as needed | pro re nata |
| q. | every | quaque |
| q.1.h., q1h | every hour | quaque hora |
| q.2.h., q2h | every 2 hours | quaque secunda hora |
| q.4.h., q4h | every 4 hours | quaque quarta hora |
| q.6.h., q6h | every 6 hours | quaque sexta hora |
| q.8.h., q8h | every 8 hours | quaque octava hora |
| q.a.m., qAM, qam | every morning | quaque ante meridiem |
| q.d., qd | every day / daily | quaque die |
| q.h.s., qhs | every night at bedtime | quaque hora somni |
| q.d.s, qds, QDS | 4 times a day | quater die sumendum |
| q.i.d, qid | 4 times a day | quater in die |
| q.h., qh | every hour, hourly | quaque hora |
| q.o.d., qod | every other day / alternate days | quaque altera die |
| q.p.m., qPM, qpm | every afternoon or evening | quaque post meridiem |
| q.s., qs | a sufficient quantity (enough) | quantum sufficiat |
| q.wk. also qw | weekly (once a week) | quaque week |
| Rx, Rx, ℞ | prescription | recipe |
| Sig., S. | directions | signa |
| Stat. | immediately, with no delay, now | statim |
| t.i.d., tid, TID | 3 times a day | ter in die |
| t.d.s., tds, TDS | take by mouth 3 times a day | ter die sumendus |
| u.d., ud | as directed | ut dictum |