T37.96XA (Underdosing of unspecified systemic anti-infectives and antiparasitics, initial encounter) compared with T37.96XS (Underdosing of unspecified systemic anti-infectives and antiparasitics, sequela), from the official CMS tabular data. T37.96XA and T37.96XS code the same injury at a different phase of treatment.
Same underlying diagnosis, different encounter phase.
The 7th character records the phase of care for the encounter being coded, so a single encounter takes one of these characters, not several. Review whether both phases belong on the same episode of care.
Source: ICD-10-CM Official Guidelines, Section I.C.19.a
Same injury, other encounter phase. T37.96XA and T37.96XS code the same injury at a different phase of treatment, set by the 7th character.
The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.
| T37.96XAUnderdosing of unspecified systemic anti-infectives and antiparasitics, initial encounter | T37.96XSUnderdosing of unspecified systemic anti-infectives and antiparasitics, sequela | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Underdosing of unspecified systemic anti-infectives and antiparasitics, initial encounter is a billable ICD-10-CM diagnosis code (T37.96A). | Underdosing of unspecified systemic anti-infectives and antiparasitics, sequela is a billable ICD-10-CM diagnosis code (T37.96S). |
| 7th character | The appropriate 7th character is to be added to each code from category T37 | The appropriate 7th character is to be added to each code from category T37 |
| Includes | adverse effect of correct substance properly administered poisoning by overdose of substance poisoning by wrong substance given or taken in error underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed | adverse effect of correct substance properly administered poisoning by overdose of substance poisoning by wrong substance given or taken in error underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed |
| Use additional code | code(s) to specify: manifestations of poisoning underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9) | code(s) to specify: manifestations of poisoning underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9) |
| Code first | , for adverse effects, the nature of the adverse effect, such as: adverse effect NOS (T88.7) | , for adverse effects, the nature of the adverse effect, such as: adverse effect NOS (T88.7) |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources