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T38.99 ICD-10-CM Code: Poisoning by, adverse effect of and underdosing of other hormone antagonists

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 · 4 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 T38.99 in the official ICD-10-CM tabular list, quoted as published.

Notes without a marker are published on T38.99 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 T38"

  • 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

T38.991A, T38.991D, T38.991S, T38.992A, T38.992D, T38.992S, T38.993A, T38.993D

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.

Code Overview

Poisoning by, adverse effect of and underdosing of other hormone antagonists is a non-billable ICD-10-CM category code (T38.99). 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. 4 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

Other codes that name T38.99 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 Excludes1 note: T48.0 — Poisoning by, adverse effect of and underdosing of oxytocic drugs (via T38.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 11 Excludes2 notes across 2 chapters: T80 — Complications following infusion, transfusion and therapeutic injection (via T38.-), T80-T88 — Complications of surgical and medical care, not elsewhere classified (T80-T88) (via T38.-), T81 — Complications of procedures, not elsewhere classified (via T38.-), T82 — Complications of cardiac and vascular prosthetic devices, implants and grafts (via T38.-), T83 — Complications of genitourinary prosthetic devices, implants and grafts (via T38.-), T84 — Complications of internal orthopedic prosthetic devices, implants and grafts (via T38.-), T85 — Complications of other internal prosthetic devices, implants and grafts (via T38.-), T86 — Complications of transplanted organs and tissue (via T38.-), T87 — Complications peculiar to reattachment and amputation (via T38.-), T88 — Other complications of surgical and medical care, not elsewhere classified (via T38.-), Y63 — Failure in dosage during surgical and medical care (via T38.-).

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 T38.-), E03.2 — Hypothyroidism due to medicaments and other exogenous substances (via T38.-), E09 — Drug or chemical induced diabetes mellitus (via T38.-), F02 — Dementia in other diseases classified elsewhere (via T38.-), G92.8 — Other toxic encephalopathy (via T38.-), G92.9 — Unspecified toxic encephalopathy (via T38.-), H35.38 — Toxic maculopathy (via T38.-), H91.0 — Ototoxic hearing loss (via T38.-), I42.7 — Cardiomyopathy due to drug and external agent (via T38.-), K22.1 — Ulcer of esophagus (via T38.-), K71 — Toxic liver disease (via T38.-), L53.0 — Toxic erythema (via T38.-), M34.2 — Systemic sclerosis induced by drug and chemical (via T38.-), N14 — Drug- and heavy-metal-induced tubulo-interstitial and tubular conditions (via T38.-), P58.4 — Neonatal jaundice due to drugs or toxins transmitted from mother or given to newborn (via T38.-), Z91.12 — Patient's intentional underdosing of medication regimen (via T38.-), Z91.13 — Patient's unintentional underdosing of medication regimen (via T38.-), Z91.14 — Patient's other noncompliance with medication regimen (via T38.-), Z91.A2 — Caregiver's intentional underdosing of patient's medication regimen (via T38.-), Z91.A3 — Caregiver's unintentional underdosing of patient's medication regimen (via T38.-).

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 99 Use Additional Code instructions across 15 chapters: D46 — Myelodysplastic syndromes (via T38.-), D52.1 — Drug-induced folate deficiency anemia (via T38.-), D59.0 — Drug-induced autoimmune hemolytic anemia (via T38.-), D59.2 — Drug-induced nonautoimmune hemolytic anemia (via T38.-), D59.39 — Other hemolytic-uremic syndrome (via T38.-), D61.1 — Drug-induced aplastic anemia (via T38.-), D64.2 — Secondary sideroblastic anemia due to drugs and toxins (via T38.-), D70.2 — Other drug-induced agranulocytosis (via T38.-), D72.12 — Drug rash with eosinophilia and systemic symptoms syndrome (via T38.-), D84.821 — Immunodeficiency due to drugs (via T38.-), D89.3 — Immune reconstitution syndrome (via T38.-), E03.2 — Hypothyroidism due to medicaments and other exogenous substances (via T38.-), E06.4 — Drug-induced thyroiditis (via T38.-), E09 — Drug or chemical induced diabetes mellitus (via T38.-), E16.0 — Drug-induced hypoglycemia without coma (via T38.-), E22.1 — Hyperprolactinemia (via T38.-), E23.1 — Drug-induced hypopituitarism (via T38.-), E24.2 — Drug-induced Cushing's syndrome (via T38.-), E25.8 — Other adrenogenital disorders (via T38.-), E27.3 — Drug-induced adrenocortical insufficiency (via T38.-), +79 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 T38.-).

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

Contextual Map

Every relationship of T38.99 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 T38.99 with these 24 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes (11)

Referenced by Code First instructions (20)

Referenced by Use Additional Code instructions (99)

  • D46 — Myelodysplastic syndromes[Use Additional Code](via T38.-): “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 T38.-): “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 T38.-): “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 T38.-): “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 T38.-): “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 T38.-): “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 T38.-): “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 T38.-): “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 91 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 T38.99 be billed directly?

No. T38.99 (Poisoning by, adverse effect of and underdosing of other hormone antagonists) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T38.99 require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T38.

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 other hormone antagonists

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 T38.99 in its code family, with their registry titles.

View all codes in the T38 family