G90.81
Billable codeSerotonin syndrome
The ICD-10 code for serotonin syndrome is G90.81.
Clinical notes
Code first
This code represents a manifestation of an underlying disease. Coding convention requires the underlying (etiology) code to be sequenced first, with this code listed second.
- 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)
Also known as
Alternate wording, synonyms, or specific conditions that fall under this code, listed to help confirm you've picked the right one.
- Serotonin toxicity
Use additional code
This code represents an underlying condition. When a related manifestation is also present, coding convention calls for an additional code to be listed after this one.
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Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •This code represents a manifestation. Documentation should identify the underlying condition, which must be coded first.
- •If the associated manifestation or related condition noted above is also documented, an additional code should be reported alongside this one.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Related codes in this category
- G90.89Other disorders of autonomic nervous system
- G90.81Serotonin syndrome
Associated MS-DRGs
G90.81 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.
Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.