Which abbreviation corresponds to the meaning 'By mouth'?

• A. Prn
• B. Ns
• C. Po
• D. Gtt(s)

Answer: (C)

By mouth is conveyed by the abbreviation Po, from per os in Latin, meaning the medication is taken orally. This route specifies ingestion through the mouth rather than injection or topical application. The other abbreviations don’t describe oral intake: Prn means “as needed,” not how the drug is given; Ns is commonly normal saline, a fluid for IV use rather than ingestion; Gtt(s) means drops (guttae), used for instillation into the eye, ear, or sometimes mouth, but not for oral administration. Po is the one that clearly indicates oral ingestion.