Oral administration
Oral administration of a tablet
Other names	By mouth, per os (PO)
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A health professional demonstrates how to offer oral medication to a dummy.

Oral administration of a liquid

Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction 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.^[1]

Terminology

Per os (/ˌpɜːrˈoʊs/; P.O.) is an adverbial phrase meaning literally from Latin "through the mouth" or "by mouth". The expression is used in medicine to describe a treatment that is taken orally (but not used in the mouth such as, for example, caries prophylaxis).^[2] The abbreviation P.O. is often used on medical prescriptions.

Scope

Oral administration includes:

• Buccal, dissolved inside the cheek
• Sublabial, dissolved under the lip
• Sublingual administration (SL), dissolved under the tongue, but due to rapid absorption many consider SL a parenteral route

Enteral medications come in various forms, including^[1] oral solid dosage (OSD) forms:^[3]

• Tablets to swallow, chew or dissolve in water or under the tongue
• Capsules and chewable capsules (with a coating that dissolves in the stomach or bowel to release the medication there)
• Time-release or sustained-release tablets and capsules (which release the medication gradually)
• Powders or granules

and oral liquid dosage forms:^[4]

• Teas
• Drops
• Liquid medications or syrups

Facilitating methods

Concomitant ingestion of water facilitates in swallowing tablets and capsules.^[5] If the substance has disagreeable taste, addition of a flavor may facilitate ingestion.^[5] Substances that are harmful to the teeth are preferably given through a straw.^[5]