What it means
Part of a set of abbreviations for the ears (AD right ear, AS left ear, AU both ears) that are easily mixed up with the eye abbreviations OD, OS and OU. Errors have led to drops meant for the ears being put in the eyes. ISMP lists all of them as error-prone.
For the nurse
Write "both ears" (or "right ear", "left ear") in full. If an order says AU, contact the prescriber to confirm before giving the drug.
Related terms
gtt
An abbreviation for drop or drops, from the Latin gutta and guttae.