2027 ICD-10-CM Diagnosis Code F43.9Reaction to severe stress, unspecified

ICD-10-CM Codes›F01–F99›F40-F48›F43

ICD-10-CM F43.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

F43.9 is a billable ICD-10-CM diagnosis code for reaction to severe stress, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 882. Coders also document this condition as psychomotor agitation. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Trauma- and stressor-related disorders.

Code Identity

ICD-10-CM Code
F43.9
Billable Status
Yes — Valid for Submission
Code Describes
Reaction to severe stress, unspecified
Short Description
Reaction to severe stress, unspecified
Same as the full description in the CMS dataset.
Parent Code
F43
Reaction to severe stress, and adjustment disorders

Code Classification

ChapterF01–F99Mental and behavioural disorders
SectionF40-F48Anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders
CategoryF43Reaction to severe stress, and adjustment disorders
This CodeF43.9Reaction to severe stress, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Psychomotor agitation
  • Stress and adjustment reaction
  • Stress due to family tension
  • Stress monitoring check done
  • Stress monitoring default
  • Stress monitoring status
  • Stress reaction with psychomotor agitation
  • Symptoms of stress

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to F43.9: its own notes plus those printed at Chapter 5. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 5 (F01-F99) Mental and behavioural disorders applies to 872 codes
  • disorders of psychological development

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

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

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 5 (F01-F99) Mental and behavioural disorders applies to 872 codes
  • symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name F43.9, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming F43.9: its condition is not part of those codes, and both may be reported when the patient has both.

  • F93.0 Separation anxiety disorder of childhood
    nonpsychotic mental disorders (F40-F48) names F40-F48, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MBD007
Trauma- and stressor-related disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Stress

Stress is how your brain and body respond to a challenge or demand. When you are stressed, your body releases certain hormones. Hormones are chemicals that travel in your bloodstream and control how different parts of your body work. The hormones that are released when you are stressed make you alert and ready to act.

The full article covers:

  • What is stress?
  • What causes long-term stress?
  • How can long term-stress harm my health?
  • How can I manage long-term stress?
  • When should I ask my health care provider for help with stress?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert F43.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
309.9 Adjustment reaction NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About F43.9Overview

What is the ICD-10 code for reaction to severe stress, unspecified?

The ICD-10-CM code for reaction to severe stress, unspecified is F43.9 (sometimes written as F439). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is F43.9 (Reaction to severe stress, and adjustment disorders) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report reaction to severe stress, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does F43.9 group to?

When reaction to severe stress, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 882 (neuroses Except Depressive), which carries a relative weight of 0.9953. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of F43.9?

Under the General Equivalence Mappings, reaction to severe stress, unspecified converts to ICD-9-CM 309.9 (adjustment reaction NOS). The mapping is approximate, so confirm the match fits the documentation.