Oral administration

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]

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


Per os (/ˌpɜːrˈs/; 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 abbreviation P.O. is often used on medical prescriptions. P.O. is also occasionally alternatively rendered per orem.


Oral administration includes:

Enteral medications come in various forms, including[1] Oral solid dosage (OSD) forms:[2]

  • 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:[3]

  • Teas
  • Drops
  • Liquid medications or syrups

Facilitating methodsEdit

Concomitant ingestion of water facilitates in swallowing tablets and capsules.[4] If the substance has disagreeable taste, addition of a flavor may facilitate ingestion.[4] Substances that are harmful to the teeth are preferably given through a straw.[4]

See alsoEdit


  1. ^ a b Institute for Quality and Efficiency in Health Care. "Oral medications". Informed Health Online. Institute for Quality and Efficiency in Health Care. Retrieved 22 June 2013.
  2. ^ Jacobs, Terry; Signore, Andrew A. (2016-08-19). Good Design Practices for GMP Pharmaceutical Facilities. CRC Press. ISBN 978-1-4822-5891-2.
  3. ^ McCabe-Sellers, Beverly; Frankel, Eric H.; Wolfe, Jonathan J. (2003-04-29). Handbook of Food-Drug Interactions. CRC Press. ISBN 978-0-203-49024-2.
  4. ^ a b c TheFreeDictionary > oral administration of medication Citing: Mosby's Medical Dictionary, 8th edition. 2009