ICD-10-CM > S00-T88 > T36-T50 > T40 > T40.9 > T40.90 > T40.906 T40.906 Underdosing of unspecified psychodysleptics [hallucinogens] Non-Billable/Non-Specific Codes T40.906A..., initial encounterT40.906D..., subsequent encounterT40.906S..., sequela