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.
A health professional demonstrates how to offer oral medication to a dummy.
Oral administration of a liquid
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]

Oral administration can be easier and less painful than other routes, such as injection. However, the onset of action is relatively low, and the effectiveness is reduced if it is not absorbed properly in the digestive system, or if it is broken down by digestive enzymes before it can reach the bloodstream. Some medications may cause gastrointestinal side effects, such as nausea or vomiting, when taken orally. Oral administration can also only be applied to conscious patients, and patients able to swallow.[2]


Per os (/ˌpɜːrˈs/; 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).[3] The abbreviation P.O. is often used on medical prescriptions.


Oral administration includes:

Enteral medications come in various forms, including[1] oral solid dosage (OSD) forms:[4]

and oral liquid dosage forms:[5]

Facilitating methods

Concomitant ingestion of water facilitates in swallowing tablets and capsules.[6] If the substance has disagreeable taste, addition of a flavor may facilitate ingestion.[6] Substances that are harmful to the teeth are preferably given through a straw.[6]

See also


  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. ^ "Oral Administration of Drugs: Advantages and Disadvantages". Retrieved December 8, 2022.
  3. ^ Hunnius Pharmazeutisches Wörterbuch (in German) (8th ed.). Berlin: Walter de Gruyter. 1998. p. 1048. ISBN 3-11-015793-4.
  4. ^ Jacobs, Terry; Signore, Andrew A. (2016-08-19). Good Design Practices for GMP Pharmaceutical Facilities. CRC Press. ISBN 978-1-4822-5891-2.
  5. ^ 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.
  6. ^ a b c TheFreeDictionary > oral administration of medication Citing: Mosby's Medical Dictionary, 8th edition. 2009