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F43.9 ICD-10-CM Code: Reaction to severe stress, unspecified

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

Coding at a Glance

Tabular directives
2 inclusion terms

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 v44, Appendix B.

  • MS-DRG 882 — NEUROSES EXCEPT DEPRESSIVE (MDC 19)

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 F43.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Trauma and stressor-related disorder, NOS
  • Unspecified trauma and stressor-related disorder

Coder workflow for F43.9

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

Before you code F43.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, F43.9 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by severity. 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).

    ReviewF43.0, F43.1, F43.2, F43.8

    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 — F43.9 is appropriate when the documentation goes no further.

    ReviewF43.0, F43.1, F43.2, F43.8

Consider F43.9. Then 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).
Severity
Mild, moderate or severe as the provider states it; severity is not inferred from the clinical picture.
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.

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).

ReviewF43.0, F43.1, F43.2, F43.8

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

Reaction to severe stress, unspecified is a billable ICD-10-CM diagnosis code (F43.9).

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 (6)

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

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

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 F43.9 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 Excludes2 note: F93.0 — Separation anxiety disorder of childhood (via F43.-).

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

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 1 MS-DRG: DRG 882 (MDC 19).

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

Clinical classification (AHRQ CCSR):MBD007 — Trauma- and stressor-related disorders (default).

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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Trauma- and stressor-related disorders).

F43.20 — Adjustment disorder, unspecified, F43.21 — Adjustment disorder with depressed mood, F43.22 — Adjustment disorder with anxiety, F43.23 — Adjustment disorder with mixed anxiety and depressed mood, F43.24 — Adjustment disorder with disturbance of conduct, F43.25 — Adjustment disorder with mixed disturbance of emotions and conduct, F43.29 — Adjustment disorder with other symptoms, F43.8 — Other reactions to severe stress, F43.81 — Prolonged grief disorder, F43.89 — Other reactions to severe stress, F44.0 — Dissociative amnesia, F44.1 — Dissociative fugue, F44.2 — Dissociative stupor, F44.4 — Conversion disorder with motor symptom or deficit, F44.5 — Conversion disorder with seizures or convulsions, F44.6 — Conversion disorder with sensory symptom or deficit, F44.7 — Conversion disorder with mixed symptom presentation, F44.81 — Dissociative identity disorder, F44.89 — Other dissociative and conversion disorders, F44.9 — Dissociative and conversion disorder, unspecified, +7 more

Same Index main term, other category

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

F23 — Brief psychotic disorder (paranoid), F30.8 — Other manic episodes (hypomanic), F31.4 — Bipolar disorder, current episode depressed, severe, without psychotic features (depressive, affective), F32.3 — Major depressive disorder, single episode, severe with psychotic features (depressive, psychotic), F32.9 — Major depressive disorder, single episode, unspecified (depressive), F33.9 — Major depressive disorder, recurrent, unspecified (depressive, affective, recurrent episode), F34.1 — Dysthymic disorder (neurotic-depressive), F40.9 — Phobic anxiety disorder, unspecified (fear), F41.1 — Generalized anxiety disorder (anxiety), F42.8 — Other obsessive-compulsive disorder (compulsive), F44.9 — Dissociative and conversion disorder, unspecified (hysterical), F45.20 — Hypochondriacal disorder, unspecified (hypochondriacal), F48.1 — Depersonalization-derealization syndrome (psychoneurotic, depersonalization), F48.8 — Other specified nonpsychotic mental disorders (asthenic), F48.9 — Nonpsychotic mental disorder, unspecified (neurotic), F60.7 — Dependent personality disorder (passive dependency), F93.8 — Other childhood emotional disorders (fear, child), F94.0 — Selective mutism (adjustment, with, mutism, elective), F99 — Mental disorder, not otherwise specified (psychogenic), G97.1 — Other reaction to spinal and lumbar puncture (spinal puncture), +40 more

Contextual Map

Every relationship of F43.9 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 F43.9 with this related code in Claim Check

Hierarchy

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 19 — Mental Diseases and Disorders[MDC crossing]: “Mental Diseases and Disorders — 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 · FY2027

Index entries

  • Disorder (of), stress[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disorder (of), trauma and stressor-related NOS[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disorder (of), trauma and stressor-related NOS, unspecified[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Reaction, stress (severe)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Stress[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Stress, reaction[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (17)

Change history

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

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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 — v44 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. "F43.9 — Reaction to severe stress, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/f43.9-reaction-to-severe-stress-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Reaction to severe stress, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, 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 F43.9 in its code family, with their registry titles.

View all codes in the F43 family