ICD-10-CM > S00-T88 > T36-T50 > T48 > T48.9 > T48.90 > T48.906 T48.906 Underdosing of unspecified agents primarily acting on the respiratory system Non-Billable/Non-Specific Codes T48.906A..., initial encounterT48.906D..., subsequent encounterT48.906S..., sequela