R40.4 Transient alteration of awareness

Billable ICD-10-CM code, FY2026.

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) 884 in MDC 19.

Approximate ICD-9-CM (GEMs)

• 780.02 Transient alteration of awareness

Code annotations containing back-references to R40.4

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 R40.4

• Alteration (of), Altered › awareness › transient

Nearby codes

• R40.2442 Other coma, without documented Glasgow coma scale score, or with partial score reported, at arrival to emergency department
• R40.2443 Other coma, without documented Glasgow coma scale score, or with partial score reported, at hospital admission
• R40.2444 Other coma, without documented Glasgow coma scale score, or with partial score reported, 24 hours or more after hospital admission
• R40.2A Nontraumatic coma due to underlying condition
• R40.3 Persistent vegetative state
• R40.4 Transient alteration of awareness (this code)