ICD-10-CM > S00-T88 > T36-T50 > T40 > T40.4 > T40.49 > T40.496 T40.496 Underdosing of other synthetic narcotics Non-Billable/Non-Specific Codes T40.496A..., initial encounterT40.496D..., subsequent encounterT40.496S..., sequela