MedTerms Medical Dictionary

p.r.n.: Abbreviation meaning "when necessary" (from the Latin "pro re nata", for an occasion that has arisen, as circumstances require, as needed). One of a number of hallowed abbreviations of Latin terms that have traditionally been used in prescriptions. Some others:

• a.c. = before meals (from "ante cibum", before meals)
• b.i.d. = twice a day (from "bis in die", twice a day)
• gtt. = drops (from "guttae", drops)
• p.c. = after meals (from "post cibum", after meals)
• p.o. = by mouth, orally (from "per os", by mouth)
• q.d. = once a day (from "quaque die", once a day)
• q.i.d. = four times a day (from "quater in die", 4 times a day)
• q._h.: If a medicine is to be taken every so-many hours (from "quaque", every and the "h" indicating the number of hours)
• q.h. = every hour
• q.2h. = every 2 hours
• q.3h. = every 3 hours
• q.4h. = every 4 hours
• t.i.d. = three times a day (from "ter in die", 3 times a day)
• ut dict. = as directed (from "ut dictum", as directed)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Find a medical definition by using the A-Z listing (select a letter)

Copyright © 1996-2003 MedicineNet, Inc. All rights reserved.
MedicineNet, Inc. does not endorse any of the services or products offered on this page.

Information in the MedTerms Medical Dictionary is provided for informational purposes only and is not a substitute for professional medical advice. You should not use this information for diagnosing or treating a medical or health condition. You should carefully read all product packaging. If you have or suspect you have a medical problem, promptly contactyour professional healthcare provider.

Use the A-Z listing (select a letter) to find a definition

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z