M35.81 Multisystem inflammatory syndrome
The ICD-10-CM code for Multisystem inflammatory syndrome is M35.81 (FY2026). It is a billable, claim-ready diagnosis code.
Classification
- Section
- M30-M36: Systemic connective tissue disorders (M30-M36)
- Category M35
- 26 codes (23 billable)
- FY2026 Status
- Stable since FY2024
Also Known As
ICD-10-CM Alphabetic Index entries that lead to M35.81:
- MIS-C
- Multisystem inflammatory syndrome (in adult) (in children)
- PIMS
- Pediatric inflammatory multisystem syndrome
- MIS-A
- Syndrome › pediatric inflammatory multisystem
- Syndrome › multisystem inflammatory (in adults) (in children)
Inclusion Terms
- MIS-A
- MIS-C
- Multisystem inflammatory syndrome in adults
- Multisystem inflammatory syndrome in children
- Pediatric inflammatory multisystem syndrome
- PIMS
U.S. Hospital Utilization
- An estimated 1,445 U.S. inpatient stays in 2023 included M35.81 among the documented diagnoses.
- 430 stays listed it as the principal diagnosis.
Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.
Official Coding Guidelines
MIS with COVID-19: U07.1 principal/first-listed + M35.81 addl(l) Multisystem Inflammatory Syndrome For individuals with multisystem inflammatory syndrome (MIS) and COVID-19, assign code U07.1, COVID-19, as the principal/first-listed diagnosis and assign code M35.81, Multisystem inflammatory syndrome, as an additional diagnosis.
History of COVID-19 develops MIS: assign M35.81 and U09.9If an individual with a history of COVID-19 develops MIS, assign codes M35.81, Multisystem inflammatory syndrome, and U09.9, Post COVID-19 condition, unspecified.
Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026