ICD-10 G90.81
Billable / SpecificSerotonin syndrome
About ICD-10-CM G90.81
ICD-10-CM code G90.81 represents Serotonin syndrome. This is a billable/specific code in the Nervous System chapter (block G90). The 2026 edition of ICD-10-CM G90.81 became effective on October 1, 2025.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under G90.81. Per CMS ICD-10-CM Tabular 2026.
- Serotonin toxicity
Use Additional Code
When coding G90.81, also report these additional codes when applicable.
- code for adverse effect, if applicable, to identify drug, such as:
- linezolid (T36.8X5)
- monoamine oxidase inhibitors (T43.1X5)
- selective serotonin and norepinephrine reuptake inhibitors [SSNRI] (T43.215)
- selective serotonin reuptake inhibitors [SSRI] (T43.225)
Coding Notes
Code First
- poisoning due to drug or toxin, such as:
- linezolid (T36.8X- with sixth character 1-4)
- monoamine oxidase inhibitors (T43.1X with sixth character 1-4)
- selective serotonin and norepinephrine reuptake inhibitors [SSNRI] (T43.21 with sixth character 1-4)
- selective serotonin reuptake inhibitors [SSRI] (T43.22 with sixth character 1-4)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for G90.81
Local Coverage Determinations (LCDs) from CMS MACs that list G90.81 as a covered diagnosis.
Showing top 10 of 53 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G90.81.
2 Cigna
3 Medicare
CPT Codes Commonly Billed with G90.81
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.
Codes Adjacent To G90.81
Other codes in section G89-G99 (Other disorders of the nervous system).
ICD-10 G90.81, Billing FAQ
Is ICD-10 code G90.81 billable? +
Yes, G90.81 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 G90.81? +
ICD-10 G90.81 includes: Serotonin toxicity.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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