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T41.20 ICD-10-CM Code: Poisoning by, adverse effect of and underdosing of unspecified general anesthetics

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
4 inclusion terms · 7 Excludes1 · 5 Excludes2 · 4 use-additional codes · 7 code-first instructions

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T41.20 in the official ICD-10-CM tabular list, quoted as published.

Notes without a marker are published on T41.20 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • 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

Source: inherited from T36-T50

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from T36-T50

Code First

Underlying conditions that must be sequenced before this code.

  • Code first, for adverse effects, the nature of the adverse effect, such as:
  • adverse effect NOS (T88.7)
  • aspirin gastritis (K29.-)
  • blood disorders (D56-D76)
  • contact dermatitis (L23-L25)
  • dermatitis due to substances taken internally (L27.-)
  • nephropathy (N14.0-N14.2)
    N14.0-N14.2: N14.0, N14.1, N14.11, N14.19, N14.2

Source: inherited from T36-T50

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code(s) to specify:
  • manifestations of poisoning
  • underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9)
    Y63.8-Y63.9: Y63.8, Y63.9
  • underdosing of medication regimen (Z91.12-, Z91.13-)

Source: inherited from T36-T50

7th Character Guide

"The appropriate 7th character is to be added to each code from category T41"

  • A — initial encounter
  • D — subsequent encounter
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

T41.201A, T41.201D, T41.201S, T41.202A, T41.202D, T41.202S, T41.203A, T41.203D

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for T41.20

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

Before you code T41.20

  1. T41.20 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewT41.201, T41.202, T41.203, T41.204, T41.205

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. Unspecified does not mean incorrect. When the record gives no greater specificity, T41.20 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).

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

  3. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. T41.20 is not valid without one. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  4. Confirm whether the documentation describes a poisoning, an adverse effect of a correctly prescribed and administered drug, an underdosing, or a toxic effect, and the intent where the record states it: the Table of Drugs and Chemicals separates these by column, and the sequencing differs for each. Poisoning, adverse effect and underdosing guidelines (Guidelines I.C.19.e).

    See the Table of Drugs and Chemicals entries · Guide: Poisoning vs adverse effect vs underdosing →

  5. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with T41.20. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support one of the more specific codes beneath T41.20?
    Yes → Select that code and continue the checks below on its own page.
    No → T41.20 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewT41.201, T41.202, T41.203, T41.204, T41.205

  2. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — T41.20 is appropriate when the documentation goes no further.
  3. Does the documentation support a condition named in T41.20’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewT42.4, T40.5, O29, O74, O89, O29.3

  4. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then T41.20.
    No → Continue; do not add an underlying condition the record does not document.

    ReviewT88.7, K29, L27

  5. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider T41.20. 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).
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
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.
External cause, place and activity
For the external cause codes reported with the injury or poisoning, where documented (Guidelines I.C.20.a).
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

  • Excludes1 — check before selecting T41.20(7 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with T41.20: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareT42.4, T40.5, O29, O74, O89, O29.3

    See the official tabular notes · Guidelines I.A.12.a

  • Excludes2 — not part of T41.20(5 notes)

    Coding workflow: The conditions named in this note are not included in T41.20. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareF55, D84.821

    See the official tabular notes · Guidelines I.A.12.b

  • Code First — sequencing check(7 notes)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before T41.20. Do not add an underlying condition the record does not document.

    ReviewT88.7, K29, L27

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

  • Use Additional Code — after identifying T41.20(4 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with T41.20 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewY63.6, Z91.12, Z91.13

    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 subcategory for a sibling that names the missing detail.

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).

Documentation: Both the condition T41.20 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewT42.4, T40.5, O29, O74, O89, O29.3

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

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

Poisoning by, adverse effect of and underdosing of unspecified general anesthetics is a non-billable ICD-10-CM category code (T41.20). A more specific billable subcode must be selected for claims submission.

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

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
  2. Sequencing: 7 Code First instructions — the underlying condition is sequenced before this code when present. See the Code First notes
  3. 4 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  4. 7 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  5. 5 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

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 T41.20 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 11 Excludes2 notes across 2 chapters: T80 — Complications following infusion, transfusion and therapeutic injection (via T41.-), T80-T88 — Complications of surgical and medical care, not elsewhere classified (T80-T88) (via T41.-), T81 — Complications of procedures, not elsewhere classified (via T41.-), T82 — Complications of cardiac and vascular prosthetic devices, implants and grafts (via T41.-), T83 — Complications of genitourinary prosthetic devices, implants and grafts (via T41.-), T84 — Complications of internal orthopedic prosthetic devices, implants and grafts (via T41.-), T85 — Complications of other internal prosthetic devices, implants and grafts (via T41.-), T86 — Complications of transplanted organs and tissue (via T41.-), T87 — Complications peculiar to reattachment and amputation (via T41.-), T88 — Other complications of surgical and medical care, not elsewhere classified (via T41.-), Y63 — Failure in dosage during surgical and medical care (via T41.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 20 Code First instructions across 13 chapters: D64.2 — Secondary sideroblastic anemia due to drugs and toxins (via T41.-), E03.2 — Hypothyroidism due to medicaments and other exogenous substances (via T41.-), E09 — Drug or chemical induced diabetes mellitus (via T41.-), F02 — Dementia in other diseases classified elsewhere (via T41.-), G92.8 — Other toxic encephalopathy (via T41.-), G92.9 — Unspecified toxic encephalopathy (via T41.-), H35.38 — Toxic maculopathy (via T41.-), H91.0 — Ototoxic hearing loss (via T41.-), I42.7 — Cardiomyopathy due to drug and external agent (via T41.-), K22.1 — Ulcer of esophagus (via T41.-), K71 — Toxic liver disease (via T41.-), L53.0 — Toxic erythema (via T41.-), M34.2 — Systemic sclerosis induced by drug and chemical (via T41.-), N14 — Drug- and heavy-metal-induced tubulo-interstitial and tubular conditions (via T41.-), P58.4 — Neonatal jaundice due to drugs or toxins transmitted from mother or given to newborn (via T41.-), Z91.12 — Patient's intentional underdosing of medication regimen (via T41.-), Z91.13 — Patient's unintentional underdosing of medication regimen (via T41.-), Z91.14 — Patient's other noncompliance with medication regimen (via T41.-), Z91.A2 — Caregiver's intentional underdosing of patient's medication regimen (via T41.-), Z91.A3 — Caregiver's unintentional underdosing of patient's medication regimen (via T41.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 103 Use Additional Code instructions across 15 chapters: D46 — Myelodysplastic syndromes (via T41.-), D52.1 — Drug-induced folate deficiency anemia (via T41.-), D59.0 — Drug-induced autoimmune hemolytic anemia (via T41.-), D59.2 — Drug-induced nonautoimmune hemolytic anemia (via T41.-), D59.39 — Other hemolytic-uremic syndrome (via T41.-), D61.1 — Drug-induced aplastic anemia (via T41.-), D64.2 — Secondary sideroblastic anemia due to drugs and toxins (via T41.-), D70.2 — Other drug-induced agranulocytosis (via T41.-), D72.12 — Drug rash with eosinophilia and systemic symptoms syndrome (via T41.-), D84.821 — Immunodeficiency due to drugs (via T41.-), D89.3 — Immune reconstitution syndrome (via T41.-), E03.2 — Hypothyroidism due to medicaments and other exogenous substances (via T41.-), E06.4 — Drug-induced thyroiditis (via T41.-), E09 — Drug or chemical induced diabetes mellitus (via T41.-), E16.0 — Drug-induced hypoglycemia without coma (via T41.-), E22.1 — Hyperprolactinemia (via T41.-), E23.1 — Drug-induced hypopituitarism (via T41.-), E24.2 — Drug-induced Cushing's syndrome (via T41.-), E25.8 — Other adrenogenital disorders (via T41.-), E27.3 — Drug-induced adrenocortical insufficiency (via T41.-), +83 more.

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

Referenced by 1 Code Also instruction: Z91.1 — Patient's noncompliance with medical treatment and regimen (via T41.-).

These codes suggest coding this condition alongside when both are present.

Contextual Map

Every relationship of T41.20 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 T41.20 with these 24 related codes in Claim Check

Hierarchy

Referenced by Excludes2 notes (11)

Referenced by Code First instructions (20)

Referenced by Use Additional Code instructions (103)

  • D46 — Myelodysplastic syndromes[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D52.1 — Drug-induced folate deficiency anemia[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D59.0 — Drug-induced autoimmune hemolytic anemia[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D59.2 — Drug-induced nonautoimmune hemolytic anemia[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D59.39 — Other hemolytic-uremic syndrome[Use Additional Code](via T41.-): “code, if applicable, for adverse effect to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D61.1 — Drug-induced aplastic anemia[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D64.2 — Secondary sideroblastic anemia due to drugs and toxins[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • D70.2 — Other drug-induced agranulocytosis[Use Additional Code](via T41.-): “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • and 95 more

Referenced by Code Also instructions

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Can T41.20 be billed directly?

No. T41.20 (Poisoning by, adverse effect of and underdosing of unspecified general anesthetics) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T41.20 require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T41.

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
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

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Poisoning by, adverse effect of and underdosing of unspecified general anesthetics

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T41.20 in its code family, with their registry titles.

View all codes in the T41 family