Dental Hygiene Pharmacology Practice Exam 2026 – Your All-in-One Guide to Exam Success!

P.O. denotes the route of administration. It comes from the Latin term per os, meaning “by mouth.” When a prescription uses P.O., it tells you to take the medication orally by swallowing it, not by injection, inhalation, or topical application. The other options describe timing or different routes, so they don’t fit the meaning of P.O. in dosage instructions.