ICD-10-CM 2027
ICD-10 code for Somnolence
From the official ICD-10-CM alphabetic index entry “Somnolence”. Page updated September 29, 2026.
About coding Somnolence
The ICD-10-CM code for Somnolence is R40.0 (Somnolence). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on R40.0.
Within R40 (Somnolence, stupor and coma), R40.0 is specifically for Somnolence. Related codes cover stupor (R40.1), coma (R40.2), persistent vegetative state (R40.3) and transient alteration of awareness (R40.4).
Don't report R40.0 together with the conditions in its Excludes1 note: coma (R40.2-).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific Somnolence codes (official index)
- nonorganic origin F51.11 — Primary hypersomnia
Don't confuse with (Excludes1 for R40.0)
- coma (R40.2-)
Common questions about Somnolence ICD-10 codes
What is the ICD-10 code for Somnolence?
- R40.0 — Somnolence. More specific codes apply when the documentation supports them: F51.11.
What is the ICD-10 code for nonorganic origin somnolence?
- F51.11 — Primary hypersomnia.
Is R40.0 billable?
- Yes. R40.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can R40.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict R40.0 as a principal diagnosis.
Is R40.0 a CC or MCC?
- No. R40.0 is neither a CC nor an MCC under MS-DRG v44.0.