2027 ICD-10-CM Diagnosis Code F05Delirium due to known physiological condition
ICD-10-CM Codes›F01–F99›F01-F09›F05
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not a Principal Diagnosis
- Not Chronic
F05 is a billable ICD-10-CM diagnosis code for delirium due to known physiological condition. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 880. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neurocognitive disorders.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for F05.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute confusional state, of endocrine origin
- Acute confusional state, of infective origin
- Acute confusional state, of metabolic origin
- Acute confusional state, post-traumatic
- Delirium due to hepatic encephalopathy
- Delirium of mixed origin
- Hyperactive behavior
- Hyperactive postoperative delirium
- Hypoactive postoperative delirium
- Mixed hyperactive hypoactive postoperative delirium
- Post-injection delirium sedation syndrome
- Postoperative confusion
- Postoperative delirium
- Postseizure confusion
- Postseizure delirium
- Senile dementia with delirium
- Sundowning
- Toxic confusional state
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to F05: its own notes plus those printed at block F01-F09 and 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.
- 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.
- Acute or subacute brain syndrome
- Acute or subacute confusional state (nonalcoholic)
- Acute or subacute infective psychosis
- Acute or subacute organic reaction
- Acute or subacute psycho-organic syndrome
- Delirium of mixed etiology
- Delirium superimposed on dementia
- Sundowning
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- delirium NOS (R41.0)
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.
Code First
The underlying condition named in the note is sequenced before this code.
- the underlying physiological condition, such as:
- dementia (F03.9-)
Notes
General instructions on how these codes are used.
- This block comprises a range of mental disorders grouped together on the basis of their having in common a demonstrable etiology in cerebral disease, brain injury, or other insult leading to cerebral dysfunction. The dysfunction may be primary, as in diseases, injuries, and insults that affect the brain directly and selectively; or secondary, as in systemic diseases and disorders that attack the brain only as one of the multiple organs or systems of the body that are involved.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name F05, its category, or a range that includes it.
Applicable To 1
These notes mention F05.
- O99.34 Other mental disorders complicating pregnancy, childbirth, and the puerperium
Excludes1 1
These codes carry an Excludes1 note naming F05: they are not reported together with it, unless the two conditions are unrelated.
- R41.0 Disorientation, unspecifieddelirium due to known physiological condition (F05)
Excludes2 4
These codes carry an Excludes2 note naming F05: its condition is not part of those codes, and both may be reported when the patient has both.
Use Additional Code 2
These codes say to use an additional code from the note, and F05 is one of the codes named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) R41.0
Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) F03.90
Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) G40.909
twilight F05
Insanity, insane See Also: Psychosis;
Senile, senility See Also: condition; R41.81
epileptic F05
Sundowning F05
Syndrome See Also: Disease;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Delirium Due to a General Medical Condition
a disorder characterized by the acute and sudden development of changes in attention, memory, language and/or perception that can be etiologically linked to the direct physiological consequences of a general medical condition.
Patient EducationClinical
Delirium
Delirium is a mental state in which you are confused, disoriented, and not able to think or remember clearly. It usually starts suddenly. It is often temporary and treatable.
The full article covers:
- What is delirium?
- What causes delirium?
- Who is more likely to get delirium?
- What are the symptoms of delirium?
- How is delirium diagnosed?
- What are the treatments for delirium?
- Can delirium be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert F05 to ICD-9-CMHistory
Code HistoryHistory
Questions About F05Overview
What is the ICD-10 code for delirium due to known physiological condition?
The ICD-10-CM code for delirium due to known physiological condition is F05. It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is F05 (Delirium due to known physiological condition) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report delirium due to known physiological condition on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does F05 group to?
On inpatient claims, delirium due to known physiological condition maps to MS-DRG 880 (acute Adjustment Reaction and Psychosocial Dysfunction), which carries a relative weight of 0.9306. Higher weights mean higher Medicare reimbursement.
Is F05 a CC or MCC?
CMS lists F05 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.
Can F05 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because delirium due to known physiological condition describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
