ICD-10-CM > S00-T88 > T36-T50 > T40 > T40.6 > T40.60 > T40.606 T40.606 Underdosing of unspecified narcotics Non-Billable/Non-Specific Codes T40.606A..., initial encounterT40.606D..., subsequent encounterT40.606S..., sequela