ICD-10 R40.0
Billable / SpecificSomnolence
About ICD-10-CM R40.0
ICD-10-CM code R40.0 represents Somnolence. This is a billable/specific code in the Symptoms, Signs, and Abnormal Findings chapter (block R40). The 2026 edition of ICD-10-CM R40.0 became effective on October 1, 2025.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under R40.0. Per CMS ICD-10-CM Tabular 2026.
- Drowsiness
Type 1 Excludes
Pure excludes, these codes can never be coded together with R40.0. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- coma (R40.2-)
Medicare LCD Coverage for R40.0
Local Coverage Determinations (LCDs) from CMS MACs that list R40.0 as a covered diagnosis.
Showing top 10 of 426 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing R40.0.
1 Cigna
5 Medicare
CPT Codes Commonly Billed with R40.0
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert R40.0 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| R40.0 | 78009 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To R40.0
Other codes in section R40-R46 (Symptoms and signs involving cognition, perception, emotional state and behavior).
ICD-10 R40.0, Billing FAQ
Is ICD-10 code R40.0 billable? +
Yes, R40.0 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to R40.0? +
ICD-10 R40.0 includes: Drowsiness.
What codes are Type 1 Excludes for R40.0? +
Type 1 Excludes (never code together with R40.0): coma (R40.2-)
What ICD-9 codes does R40.0 map to? +
Per CMS GEMs, R40.0 maps to ICD-9 codes: 78009. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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