G90.81

Billable

ChapterG00–G99

Ranksubcategory

Official Description

Serotonin syndrome

Metadata & Insights

•Billable/specific code (valid for reimbursement).
•Chapter 6: Diseases of the Nervous System (G00-G99).

Instructional Notes

Includes

Serotonin toxicity

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)

Use Additional Code

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)
code, if applicable, to identify:
disseminated intravascular coagulation (D65)
hypertensive crisis (I16.-)
metabolic acidosis (E87.2-)
shock, not elsewhere classified (R57.-)
toxic encephalopathy (G92.-)
ventricular tachycardia (I47.2-)

General instructions are available for the parent sections:

View CH6 Notes View G90 Notes

Clinical Hierarchy

BillableHas subcodes

CH6Diseases of the nervous system (G00-G99)

G89-G99Other disorders of the nervous system (G89-G99)

G90Disorders of autonomic nervous system

G90.8Other disorders of autonomic nervous system

G90.81Serotonin syndromeBillable

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to G90.81:

categoryG90

Disorders of autonomic nervous system

View context instructions

chapterCH6

Diseases of the nervous system (G00-G99)

View context instructions

Code History

FY 2024: This code replaced G90.8 (Other disorders of autonomic nervous system)

MS-DRG Classification

2026 v43.1

This code is grouped within the following Diagnosis Related Group(s) for clinical reimbursement:

Cranial and Peripheral Nerve Disorders with MCC

Cranial and Peripheral Nerve Disorders without MCC

Cross Reference

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