Per os

Oral administration is a route of administration where a substance is taken through the mouth. Per os (P.O.) is sometimes used as an abbreviation for medication to be taken orally. Many medications are taken orally because they are intended to have a systemic effect, reaching different parts of the body via the bloodstream, for example.

"Per os" (/ˌpɜːrˈoʊs/; P.O.) is an adverbial phrase meaning literally from Latin "by opening" or "by way of the opening." The expression is used in medicine to describe a treatment that is taken orally. The abbreviated P.O. is often used on medical prescriptions. P.O. is also occasionally rendered per orem, which is sometimes corrupted to per oram. These are grammatically incorrect; "os" is a neuter noun of the 3rd declension and thus the accusative case is the same as the nominative case.

Oral administration is a part of enteral administration, which also includes

Enteral medications come in various forms, including:

Concomitant ingestion of water facilitates in swallowing tablets and capsules. If the substance has disagreeable taste, addition of a flavor may facilitate ingestion. Substances that are harmful to the teeth are preferably given through a straw.

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