R40.0 Somnolence

Billable ICD-10-CM code, FY2026.

Applicable to

• Drowsiness

Excludes1 (never code together)

• coma (R40.2-)

Applies from R40 Somnolence, stupor and coma

Excludes1 (never code together)

• 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)

MS-DRG index

Defines the logic of DRG(s) 080-081 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 780.09 Other alteration of consciousness (approximate)

Code annotations containing back-references to R40.0

Back-references to R40

• Type 1 Excludes: R41.82 Altered mental status, unspecified ("altered level of consciousness (R40.-)")
• Use Additional: T67.0 Heatstroke and sunstroke ("coma and stupor (R40.-)")

Diagnosis Index entries for R40.0

• Drowsiness
• Somnolence

Nearby codes

• R40 Somnolence, stupor and coma
• R40.0 Somnolence (this code)
• R40.1 Stupor
• R40.2 Coma
• R40.20 Unspecified coma
• R40.21 Coma scale, eyes open
• R40.211 Coma scale, eyes open, never