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G92.9 ICD-10-CM Code: Unspecified toxic encephalopathy

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 use-additional code · 1 code-first instruction

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 023 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITH MCC OR ANTINEOPLASTIC IMPLANT OR EPILEPSY WITH NEUROSTIMULATOR (MDC 01)
  • MS-DRG 024 — CRANIOTOMY WITH MAJOR DEVICE IMPLANT OR ACUTE COMPLEX CNS PRINCIPAL DIAGNOSIS WITHOUT MCC (MDC 01)
  • MS-DRG 091 — OTHER DISORDERS OF NERVOUS SYSTEM WITH MCC (MDC 01)
  • MS-DRG 092 — OTHER DISORDERS OF NERVOUS SYSTEM WITH CC (MDC 01)
  • MS-DRG 093 — OTHER DISORDERS OF NERVOUS SYSTEM WITHOUT CC/MCC (MDC 01)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G92.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Code First

Underlying conditions that must be sequenced before this code.

  • poisoning due to drug or toxin, if applicable, (T36-T65 with fifth or sixth character 1-4)

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Coder workflow for G92.9

MedCoder structured workflow — derived from this code’s own official record

Before you code G92.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, G92.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewG92.0, G92.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — G92.9 is appropriate when the documentation goes no further.

    ReviewG92.0, G92.8

  2. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then G92.9.
    No → Continue; do not add an underlying condition the record does not document.

Consider G92.9. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Code First — sequencing check(1 note)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before G92.9. Do not add an underlying condition the record does not document.

    See the official tabular notes · Guidelines I.A.13

  • Use Additional Code — after identifying G92.9(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with G92.9 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewG92.0, G92.8

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with G92.9?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Unspecified toxic encephalopathy is a billable ICD-10-CM diagnosis code (G92.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • MCC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name G92.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Use Additional Code instruction: G90.81 — Serotonin syndrome (via G92.-).

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 47 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 7 MS-DRGs: DRG 023 (MDC 01), DRG 024 (MDC 01), DRG 091 (MDC 01), DRG 092 (MDC 01), DRG 093 (MDC 01), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS020 — Other nervous system disorders (neither hereditary nor degenerative) (default); INJ030 — Drug induced or toxic related condition.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

B10.09 — Other human herpesvirus encephalitis, B26.2 — Mumps encephalitis, B58.2 — Toxoplasma meningoencephalitis, G04.00 — Acute disseminated encephalitis and encephalomyelitis, unspecified, G04.01 — Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM), G04.31 — Postinfectious acute necrotizing hemorrhagic encephalopathy, G04.81 — Other encephalitis and encephalomyelitis, G04.90 — Encephalitis and encephalomyelitis, unspecified, G37.4 — Subacute necrotizing myelitis of central nervous system, G92.8 — Other toxic encephalopathy, G93.40 — Encephalopathy, unspecified, G93.41 — Metabolic encephalopathy, G93.42 — Megalencephalic leukoencephalopathy with subcortical cysts, G93.43 — Leukoencephalopathy with calcifications and cysts, G93.44 — Adult-onset leukodystrophy with axonal spheroids, G93.45 — Developmental and epileptic encephalopathy, G93.49 — Other encephalopathy, G93.89 — Other specified disorders of brain, G93.9 — Disorder of brain, unspecified, G96.9 — Disorder of central nervous system, unspecified, +26 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Other nervous system disorders (neither hereditary nor degenerative), Drug induced or toxic related condition).

G91.8 — Other hydrocephalus, G91.9 — Hydrocephalus, unspecified, G92 — Toxic encephalopathy, G92.00 — Immune effector cell-associated neurotoxicity syndrome, grade unspecified, G92.01 — Immune effector cell-associated neurotoxicity syndrome, grade 1, G92.02 — Immune effector cell-associated neurotoxicity syndrome, grade 2, G92.03 — Immune effector cell-associated neurotoxicity syndrome, grade 3, G92.04 — Immune effector cell-associated neurotoxicity syndrome, grade 4, G92.05 — Immune effector cell-associated neurotoxicity syndrome, grade 5, G92.8 — Other toxic encephalopathy, G93.0 — Cerebral cysts, G93.2 — Benign intracranial hypertension, G93.3 — Postviral and related fatigue syndromes, G93.31 — Postviral fatigue syndrome, G93.32 — Myalgic encephalomyelitis/chronic fatigue syndrome, G93.39 — Other post infection and related fatigue syndromes, G93.40 — Encephalopathy, unspecified, G93.41 — Metabolic encephalopathy, G93.49 — Other encephalopathy, G93.5 — Compression of brain, +336 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Encephalopathy”, “Myelitis”; these codes share that main term but sit in a different category of the Tabular List.

G04.91 — Myelitis, unspecified, G05.4 — Myelitis in diseases classified elsewhere (in diseases classified elsewhere), G31.2 — Degeneration of nervous system due to alcohol (alcoholic), G31.82 — Leigh's disease (necrotizing, subacute), G32.89 — Other specified degenerative disorders of nervous system in diseases classified elsewhere (degenerative, in specified disease NEC), G36.0 — Neuromyelitis optica [Devic] (optic neuritis in), G37.0 — Diffuse sclerosis of central nervous system (centrolobar progressive), G37.1 — Central demyelination of corpus callosum (demyelinating callosal), G37.3 — Acute transverse myelitis in demyelinating disease of central nervous system (transverse), G37.4 — Subacute necrotizing myelitis of central nervous system (necrotizing, subacute), G93.40 — Encephalopathy, unspecified, G93.41 — Metabolic encephalopathy (septic), G93.45 — Developmental and epileptic encephalopathy (early infantile epileptic), G93.49 — Other encephalopathy (specified NEC), G93.89 — Other specified disorders of brain (postradiation), I67.2 — Cerebral atherosclerosis (arteriosclerotic), I67.4 — Hypertensive encephalopathy (hypertensive), K76.82 — Hepatic encephalopathy (hepatic), P11.1 — Other specified brain damage due to birth injury (in, birth injury), P57.0 — Kernicterus due to isoimmunization (hyperbilirubinemic, newborn, due to isoimmunization), +32 more

Contextual Map

Every relationship of G92.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G92.9 with these 9 related codes in Claim Check

Hierarchy

Code First (30)

Use Additional Code (15)

Referenced by Use Additional Code instructions

  • G90.81 — Serotonin syndrome[Use Additional Code](via G92.-): “toxic encephalopathy (G92.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Encephalopathy (acute), toxic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myelitis (acute) (ascending) (childhood) (chronic) (descending) (diffuse) (disseminated) (idiopathic) (pressure) (progressive) (spinal cord) (subacute), toxic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (9)

Change history

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G92.9 — Unspecified toxic encephalopathy." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/g92.9-unspecified-toxic-encephalopathy

Change history

  • FY2022 — October 1, 2021
    Added to the code set
    Unspecified toxic encephalopathy
    FY2022 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G92.9 in its code family, with their registry titles.

View all codes in the G92 family