Frequency
tiw
Three times weekly
Risk
ISMP lists tiw as error-prone: it may be mistaken as three times a day or twice weekly.
Safer Alternative
Write "3 times weekly"
Example
tiw misread as tid
Three times weekly
ISMP lists tiw as error-prone: it may be mistaken as three times a day or twice weekly.
Write "3 times weekly"
tiw misread as tid