ICD-10-CM 2027
ICD-10 code for Sundowning
F05
Delirium due to known physiological condition
From the official ICD-10-CM alphabetic index entry “Sundowning”. Page updated September 29, 2026.
About coding Sundowning
The ICD-10-CM code for Sundowning is F05 (Delirium due to known physiological condition).
Don't report F05 together with the conditions in its Excludes1 note: delirium NOS (R41.0).
The conditions in its Excludes2 note aren't part of F05, but may be coded alongside it if the patient has both: delirium tremens alcohol-induced or unspecified (F10.231, F10.921).
Code first the underlying physiological condition, such as: dementia (F03.9-).
Don't confuse with (Excludes1 for F05)
- delirium NOS (R41.0)
Common questions about Sundowning ICD-10 codes
What is the ICD-10 code for Sundowning?
- F05 — Delirium due to known physiological condition.
Is F05 billable?
- Yes. F05 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F05 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is F05 a CC or MCC?
- F05 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.