Which abbreviation indicates that a medication should be taken by mouth?

The abbreviation that indicates a medication should be taken by mouth is "PO," which stands for "per os" in Latin, meaning "by mouth." This term is commonly used in prescriptions and medical instructions to specify that a medication is intended for oral administration, which is a standard and widely recognized route of drug administration. Using "PO" helps ensure clarity in communication among healthcare providers and patients, emphasizing that the medication should be swallowed rather than given by other routes, such as intravenous or intramuscular.

In contrast, the other options refer to different meanings in medical contexts. For instance, "AD" stands for "auris dextra," referring to the right ear, and "AS" stands for "auris sinistra," indicating the left ear. "BID" means "bis in die," which translates to "twice a day" but does not specify the route of administration. Understanding these abbreviations is essential for accurately interpreting medication instructions.