T42.5X4S Poisoning by mixed antiepileptics, undetermined, sequela

ICD-10-CM Code T42.5X4S: Poisoning by mixed antiepileptics, undetermined, sequela

ICD-10-CM code T42.5X4S identifies a sequela of poisoning by mixed antiepileptics when the intent is undetermined. Public sources list this code alongside related antiepileptic poisoning codes and reference it within CMS billing and coding articles. The available excerpts do not establish clinical symptoms, treatment protocols, or payer coverage specifics. 3 4

Plain-language overview

Code T42.5X4S is described as poisoning by mixed antiepileptics, undetermined, sequela. This label is explicitly listed in the source data alongside other related antiepileptic poisoning codes. 4

What this code represents

The code T42.5X4S represents poisoning by mixed antiepileptics, undetermined, sequela. The CMS source explicitly references this exact code description within a billing and coding article for head CT services. 3 4

Coding details

The source data lists T42.5X4S and T42.5X5A separately. The code T42.5X4S denotes poisoning by mixed antiepileptics, undetermined, sequela, while T42.5X5A denotes an adverse effect of mixed antiepileptics. 4

The CMS source lists T42.5X4A as poisoning by mixed antiepileptics, undetermined, initial encounter. The source data lists T42.5X4S as poisoning by mixed antiepileptics, undetermined, sequela. 2 4

The CDC source lists T42.5x2 as poisoning by mixed antiepileptics, intentional self-harm. The CMS source lists T42.5X4A as poisoning by mixed antiepileptics, undetermined, initial encounter. 1 2

Documentation considerations

The CDC source mentions that electronic health records may lack a field when the intent of an injury or poisoning is unknown. The source also mentions that an attempt or intentional self-harm may be involved when intent is unknown. 1

Coverage and utilization context

The CMS source references code T42.5X4S within an article titled Billing and Coding: CT of the Head. The provided excerpt does not contain statements regarding the coverage implications for this code. 3

What the sources add

The CDC source discusses drug poisoning and notes that national standards are absent in some areas of electronic health records. The CMS source lists T42.5X4A as an initial encounter for undetermined poisoning by mixed antiepileptics. 1 2

Questions to verify

The provided excerpts do not establish the specific clinical symptoms, treatment protocols, or prognosis associated with poisoning by mixed antiepileptics. Verification of these clinical details requires sources outside the provided set. 1 3

Sources

1. National Health Statistics Reports — cdc.gov; accessed 2026-07-25.
2. Article - Billing and Coding: Oximetry Services (A57205) — cms.gov; accessed 2026-07-25.
3. Article - Billing and Coding: CT of the Head (A56612) — cms.gov; accessed 2026-07-25.
4. MedicareDrop — medicaredrop.com; accessed 2026-07-25.