Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.
Applicable to
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 (never code together)
delirium NOS (R41.0)
Excludes2 (not included here)
delirium tremens alcohol-induced or unspecified (F10.231, F10.921)
Code first
the underlying physiological condition, such as:
dementia (F03.9-)
Applies from F05 Delirium due to known physiological condition
Applicable to
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 (never code together)
delirium NOS (R41.0)
Excludes2 (not included here)
delirium tremens alcohol-induced or unspecified (F10.231, F10.921)
Code first
the underlying physiological condition, such as:
dementia (F03.9-)
MS-DRG index
Defines the logic of DRG(s) 880 in MDC 19.
Approximate ICD-9-CM (GEMs)
293.0 Delirium due to conditions classified elsewhere (approximate)
293.1 Subacute delirium (approximate)
Medicare Code Edits (MCE v43.1 (April 2026))
Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.
Code annotations containing back-references to F05
Back-references to F05
Type 2 Excludes: F03 Unspecified dementia ("dementia with delirium or acute confusional state (F05)")
Type 2 Excludes: F06 Other mental disorders due to known physiological condition ("delirium due to known physiological condition (F05)")
Type 2 Excludes: F63.1 Pyromania ("mental disorders due to known physiological condition (F01-F09)")
Type 2 Excludes: F63.2 Kleptomania ("stealing in mental disorders due to known physiological condition (F01-F09)")
Use Additional: G30 Alzheimer's disease ("delirium, if applicable (F05)")
Type 1 Excludes: R41.0 Disorientation, unspecified ("delirium due to known physiological condition (F05)")
Use Additional: T81.89 Other complications of procedures, not elsewhere classified ("postprocedural delirium (F05)")
Back-references to F05
Type 2 Excludes: F03 Unspecified dementia ("dementia with delirium or acute confusional state (F05)")
Type 2 Excludes: F06 Other mental disorders due to known physiological condition ("delirium due to known physiological condition (F05)")
Type 2 Excludes: F63.1 Pyromania ("mental disorders due to known physiological condition (F01-F09)")
Type 2 Excludes: F63.2 Kleptomania ("stealing in mental disorders due to known physiological condition (F01-F09)")
Use Additional: G30 Alzheimer's disease ("delirium, if applicable (F05)")
Type 1 Excludes: R41.0 Disorientation, unspecified ("delirium due to known physiological condition (F05)")
Use Additional: T81.89 Other complications of procedures, not elsewhere classified ("postprocedural delirium (F05)")
Diagnosis Index entries for F05
Confusion, confused › epileptic
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) › with › dementia
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) › due to (secondary to) › general medical condition
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) › due to (secondary to) › multiple etiologies
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) › postprocedural (postoperative)
Delirium, delirious (acute or subacute) (not alcohol- or drug-induced) › puerperal
Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › with › acute confusional state