What it means
Used in old-style orders for ear drops. ISMP lists AS, along with AD (right ear) and AU (both ears), as error-prone, because they are easily mistaken for OS, OD and OU, the abbreviations for the eyes, and for each other. Write "left ear" in full.
For the nurse
If an order uses AS, confirm with the prescriber which ear (or eye) is meant before giving the drug.
Related terms
auricle
The outer part of the ear that you can see, on the side of the head.