What does P.O. stand for in dosage instructions?

• A. By mouth
• B. At bedtime
• C. Immediately
• D. Weekly

Answer: (A)

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.