F05 vs R41.0
F05 and R41.0 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on F05
delirium NOS (R41.0)
F05
Delirium due to known physiological condition
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F01-F09
Use when the record says
- 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
Indexed under
- Sundowning
- Confusion, confused › epileptic
- Delirium, delirious › postprocedural (acute or subacute) (not alcohol- or drug-induced)
- Delirium, delirious › puerperal (acute or subacute) (not alcohol- or drug-induced)
- Epilepsy, epileptic, epilepsia › twilight (attack) (cerebral) (convulsion) (fit) (seizure)
R41.0
Disorientation, unspecified
BillableUnspecified
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R40-R46
Use when the record says
- Confusion NOS
- Delirium NOS
Indexed under
- Confusion, confused
- Delirium, delirious (acute or subacute) (not alcohol- or drug-induced)
- Disorientation
- Confusion, confused › acute
- Delirium, delirious › due to › unknown etiology (acute or subacute) (not alcohol- or drug-induced)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027