| Abbreviation | Definition |
|---|---|
| OPR | opioid pain reliever |
| ORS | oral rehydration salts |
| OSP | oral sodium phosphate |
| OTC | Over-The-Counter |
| o-t-c | over-the-counter |
| OTM | Off The Market |
| P | combined hormonal contraceptive patch |
| p.c. | after food (post cibum) [Lat.] |
| p.c. | post cibum - after meals |
| p.m. | post meridiem - evening or afternoon |
| p.o. | by mouth |
| P.O. | by mouth (per os) [Lat.] |
| p.o. | per os - by mouth or orally |
| p.r. | per rectum - by rectum |
| PA | Prophylactic Antibiotic |
| PAIN | Prescription Addiction Intervention Now |
| PAS | paramino salicylic acid |
| PBM | Pharmacy Benefit Manager |
| PCV13 | 13-valent pneumococcal conjugate vaccine |
| PCV7 | 7-valent pneumococcal conjugate vaccine |