G90.81 Serotonin syndrome

✓ Billable ICD-10-CM 2026
Open G90.81 in Web App →

The ICD-10-CM code for Serotonin syndrome is G90.81 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Section
G89-G99: Other disorders of the nervous system (G89-G99)
Category G90
27 codes (21 billable)
FY2026 Status
Introduced in FY2025

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G90.81:

  • Syndrome › serotonin
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-)

Inclusion Terms

  • Serotonin toxicity

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.6.a
Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.6.b

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

Related Codes

Parent Code

G90 Disorders of autonomic nervous system

Related Codes in G90

G90 Disorders of autonomic nervous system G90.0 Idiopathic peripheral autonomic neuropathy G90.01 Carotid sinus syncope G90.09 Other idiopathic peripheral autonomic neuropathy G90.1 Familial dysautonomia [Riley-Day] G90.2 Horner's syndrome G90.3 Multi-system degeneration of the autonomic nervous system G90.4 Autonomic dysreflexia G90.5 Complex regional pain syndrome I (CRPS I) G90.50 Complex regional pain syndrome I, unspecified G90.51 Complex regional pain syndrome I of upper limb G90.511 Complex regional pain syndrome I of right upper limb G90.512 Complex regional pain syndrome I of left upper limb G90.513 Complex regional pain syndrome I of upper limb, bilateral G90.519 Complex regional pain syndrome I of unspecified upper limb G90.52 Complex regional pain syndrome I of lower limb G90.521 Complex regional pain syndrome I of right lower limb G90.522 Complex regional pain syndrome I of left lower limb G90.523 Complex regional pain syndrome I of lower limb, bilateral G90.529 Complex regional pain syndrome I of unspecified lower limb
Search all 70,000+ ICD-10-CM codes →
Reviewed by Prajwal Shrestha, CPC, CRC
Certified Professional Coder (CPC) and Certified Risk Adjustment Coder (CRC) · AAPC Member ID 01997614 · About · Editorial policy · Content last reviewed: 2025-10-01

Get HCC Mappings, Clinical Summaries, and More

Access premium features including HCC risk adjustment, FDA drug indications, AI coding assistant, and comprehensive clinical context.

Start Free Trial