| ICD-10 Code | Description |
| T40.3X1A | Poisoning by methadone, accidental (unintentional), initial encounter |
| T40.3X1D | Poisoning by methadone, accidental (unintentional), subsequent encounter |
| T40.3X1S | Poisoning by methadone, accidental (unintentional), sequela |
| T40.3X2A | Poisoning by methadone, intentional self-harm, initial encounter |
| T40.3X2D | Poisoning by methadone, intentional self-harm, subsequent encounter |
| T40.3X2S | Poisoning by methadone, intentional self-harm, sequela |
| T40.3X3A | Poisoning by methadone, assault, initial encounter |
| T40.3X3D | Poisoning by methadone, assault, subsequent encounter |
| T40.3X3S | Poisoning by methadone, assault, sequela |
| T40.3X4A | Poisoning by methadone, undetermined, initial encounter |
| T40.3X4D | Poisoning by methadone, undetermined, subsequent encounter |
| T40.3X4S | Poisoning by methadone, undetermined, sequela |
| T40.3X5A | Adverse effect of methadone, initial encounter |
| T40.3X5D | Adverse effect of methadone, subsequent encounter |
| T40.3X5S | Adverse effect of methadone, sequela |
| T40.3X6A | Underdosing of methadone, initial encounter |
| T40.3X6D | Underdosing of methadone, subsequent encounter |
| T40.3X6S | Underdosing of methadone, sequela |
