ICD-10-CM > S00-T88 > T36-T50 > T44 > T44.9 > T44.99 > T44.996 T44.996 Underdosing of other drug primarily affecting the autonomic nervous system Non-Billable/Non-Specific Codes T44.996A..., initial encounterT44.996D..., subsequent encounterT44.996S..., sequela