F43.9 Reaction to severe stress, unspecified

✓ Billable ICD-10-CM 2026
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The ICD-10-CM code for Reaction to severe stress, unspecified is F43.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Section
F40-F48: Anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders (F40-F48)
Category F43
18 codes (14 billable)
FY2026 Status
Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to F43.9:

  • Stress
  • Stress › reaction
  • Disorder (of) › stress
  • Disorder (of) › trauma and stressor-related NOS
  • Reaction › stress (severe)
  • Disorder (of) › trauma and stressor-related NOS › unspecified

Inclusion Terms

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

U.S. Hospital Utilization

  • An estimated 22,115 U.S. inpatient stays in 2023 included F43.9 among the documented diagnoses.
  • 1,255 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Pain disorders related to psychological factors (TOC entry)

a. Pain disorders related to psychological factors ..................................................................... 43

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.5.a
Psychoactive substance use disorders (TOC entry)

b. Mental and behavioral disorders due to psychoactive substance use ................................... 43

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.5.b

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

Related Codes

Parent Code

F43 Reaction to severe stress, and adjustment disorders

Related Codes in F43

F43 Reaction to severe stress, and adjustment disorders F43.0 Acute stress reaction F43.1 Post-traumatic stress disorder (PTSD) F43.10 Post-traumatic stress disorder, unspecified F43.11 Post-traumatic stress disorder, acute F43.12 Post-traumatic stress disorder, chronic F43.2 Adjustment 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
Search all 70,000+ ICD-10-CM codes →
Reviewed by Prajwal Shrestha, CPC, CRC
Certified Professional Coder (CPC) and Certified Risk Adjustment Coder (CRC) · AAPC Member ID 01997614 · About · Editorial policy · Content last reviewed: 2025-10-01

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