medication prn definition
Medicines that are taken âas neededâ are known as âPRNâ medicines. âPRNâ is a Latin term that stands for âpro re nata,â which means âas the thing is needed.â. Itâs important to know the difference between daily and âas neededâ medicines.hese instructions should include the following information: 1  How much medicine you can take in a set period of time. 2  When to take your PRN medication. 3  When to take scheduled and PRN medications for a single health problem.