2026 ICD-10-CM Diagnosis Code B33.23Viral pericarditis

ICD-10-CM Codes›A00–B99›B25-B34›B33

ICD-10-CM B33.23
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B33.23 is a billable ICD-10-CM diagnosis code for viral pericarditis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 17 closely related codes. Coders also document this condition as acute pericarditis caused by human coxsackievirus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pericarditis and pericardial disease and Viral infection.

Code Identity

ICD-10-CM Code
B33.23
Billable Status
Yes — Valid for Submission
Code Describes
Viral pericarditis
Short Description
Viral pericarditis
Same as the full description in the CMS dataset.
Parent Code
B33.2
Viral carditis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB25-B34Other viral diseases
CategoryB33Other viral diseases, not elsewhere classified
This CodeB33.23Viral pericarditis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute pericarditis caused by human coxsackievirus
  • Acute viral pericarditis
  • Coxsackie pericarditis
  • Viral pericarditis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR006
Pericarditis and pericardial disease
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR INF008
Viral infection
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Viral Pericarditis

    pericarditis that is caused by an infection with a viral agent.

Patient EducationClinical

Pericardial Disorders

The pericardium is a membrane, or sac, that surrounds your heart. It holds the heart in place and helps it work properly. Problems with the pericardium include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B33.23 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
074.21 Coxsackie pericarditis
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About B33.23Overview

What is the ICD-10 code for viral pericarditis?

The ICD-10-CM code for viral pericarditis is B33.23 (sometimes written as B3323). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is B33.23 (Viral carditis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report viral pericarditis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B33.23 group to?

When viral pericarditis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.

Is B33.23 a CC or MCC?

CMS lists B33.23 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 17 closely related codes in its exclusion list.

What is the ICD-9 equivalent of B33.23?

Under the General Equivalence Mappings, viral pericarditis converts to ICD-9-CM 074.21 (coxsackie pericarditis). The mapping is approximate, so confirm the match fits the documentation.