Frequency
OD
Once daily
Risk
ISMP lists OD/o.d. as error-prone when intended as once daily: it may be mistaken as right eye, leading to oral liquid medications administered in the eye.
Safer Alternative
Write "daily"
Example
OD intended as once daily misread as right eye
Source Note
OD also has a separate eye-laterality entry for right eye; write "right eye" for laterality and "daily" for frequency.