2026 ICD-10-CM Diagnosis Code R45.5Hostility

ICD-10-CM Codes›R00–R99›R40-R46›R45

ICD-10-CM R45.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R45.5 is a billable ICD-10-CM diagnosis code for hostility. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 880. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Symptoms of mental and substance use conditions.

Code Identity

ICD-10-CM Code
R45.5
Billable Status
Yes — Valid for Submission
Code Describes
Hostility
Short Description
Hostility
Same as the full description in the CMS dataset.
Parent Code
R45
Symptoms and signs involving emotional state

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR40-R46Symptoms and signs involving cognition, perception, emotional state and behavior
CategoryR45Symptoms and signs involving emotional state
This CodeR45.5Hostility

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Aggressive character
  • Bullying
  • Bullying of adult
  • Bullying of child
  • Character trait finding of level of hostility
  • Emotional bullying
  • Feeling hatred
  • Goading
  • Hostile behavior
  • Intimidation
  • Provocative behavior
  • Teasing
  • Threatening behavior
  • Verbal aggression
  • Verbally threatening behavior

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 SYM008
Symptoms of mental and substance use conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Hostility

    tendency to feel anger toward and to seek to inflict harm upon a person or group.

  • Bullying

    aggressive behavior by a more powerful party that results in physical harm to or emotional distress of the victim.

  • Cyberbullying

    bullying that takes place over digital devices like cell phones and computers. it includes sending, posting, or sharing negative, harmful, false, or mean content about someone else. it can include sharing personal or private information about someone else causing embarrassment or humiliation. (from https://www.stopbullying.gov)

  • Occupational Stress

    adverse psychological and behavioral reactions caused by the pressures and demands of employers or clients or other factors, such as the physical environment of the workplace, workplace violence; or workplace bullying.

Convert R45.5 to ICD-9-CMHistory

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

ICD-9-CM
300.9 Nonpsychotic disord 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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R45.5Overview

What is the ICD-10 code for hostility?

The ICD-10-CM code for hostility is R45.5 (sometimes written as R455). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is R45.5 (Symptoms and signs involving emotional state) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hostility on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does R45.5 group to?

When hostility is the principal diagnosis on an inpatient stay, it groups to MS-DRG 880 (acute Adjustment Reaction and Psychosocial Dysfunction), which carries a relative weight of 0.9602. Higher weights mean higher Medicare reimbursement.

Can R45.5 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the hostility is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R45.5?

Under the General Equivalence Mappings, hostility converts to ICD-9-CM 300.9 (nonpsychotic disord NOS). The mapping is approximate, so confirm the match fits the documentation.