ICD-10-CM > S00-T88 > T36-T50 > T40 > T40.4 > T40.41 T40.41 Poisoning by, adverse effect of and underdosing of fentanyl or fentanyl analogs Non-Billable/Non-Specific Codes T40.411Poisoning by fentanyl or fentanyl analogs, accidental (unintentional)T40.411A..., initial encounterT40.411D..., subsequent encounterT40.411S..., sequelaT40.412Poisoning by fentanyl or fentanyl analogs, intentional self-harmT40.412A..., initial encounterT40.412D..., subsequent encounterT40.412S..., sequelaT40.413Poisoning by fentanyl or fentanyl analogs, assaultT40.413A..., initial encounterT40.413D..., subsequent encounterT40.413S..., sequelaT40.414Poisoning by fentanyl or fentanyl analogs, undeterminedT40.414A..., initial encounterT40.414D..., subsequent encounterT40.414S..., sequelaT40.415Adverse effect of fentanyl or fentanyl analogsT40.415A..., initial encounterT40.415D..., subsequent encounterT40.415S..., sequelaT40.416Underdosing of fentanyl or fentanyl analogsT40.416A..., initial encounterT40.416D..., subsequent encounterT40.416S..., sequela