R40.0 – Somnolence

ICD-10-CM 2027 diagnosis code · Symptoms and signs involving cognition, perception, emotional state and behavior

Billable code

ICD-10-CM code R40.0

Code: R40.0 (claims format: R400)
Description: Somnolence
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
Block: R40-R46 Symptoms and signs involving cognition, perception, emotional state and behavior
Parent codes: R40

Notes for R40.0

Applicable to:

Drowsiness

Excludes1 (not coded here):

coma (R40.2-)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

R40 – Somnolence, stupor and coma

Excludes1 (not coded here):

neonatal coma (P91.5)
somnolence, stupor and coma in diabetes (E08-E13)
somnolence, stupor and coma in hepatic failure (K72.-)
somnolence, stupor and coma in hypoglycemia (nondiabetic) (E15)

Block R40-R46

Excludes2 (not included here):

symptoms and signs constituting part of a pattern of mental disorder (F01-F99)

Index terms for R40.0

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in R40

R40.1 – StuporBillable
R40.2 – ComaHeader
R40.3 – Persistent vegetative stateBillable
R40.4 – Transient alteration of awarenessBillable

Frequently asked questions

What is ICD-10 code R40.0?

R40.0 is the ICD-10-CM code for somnolence, in the block R40-R46 (Symptoms and signs involving cognition, perception, emotional state and behavior).

Is R40.0 a billable code?

Yes. R40.0 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does R40.0 belong to?

It belongs to category R40 – Somnolence, stupor and coma.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.