| Billable | No — use a more specific child code |
| Chapter | Chapter 19: Injury, poisoning and certain other consequences of external causes (S00-T88) |
| Section | Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50) |
| Parent code | T40.41 — Fentanyl or fentanyl analogs |
| Requires 7th character | Yes |