2026 ICD-10-CM Diagnosis Code K12.33Oral mucositis (ulcerative) due to radiation

ICD-10-CM Codes›K00–K95›K00-K14›K12

ICD-10-CM K12.33
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K12.33 is a billable ICD-10-CM diagnosis code for oral mucositis (ulcerative) due to radiation. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 157 through 159. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury, Diseases of mouth; excluding dental, and Nontraumatic dental conditions.

Code Identity

ICD-10-CM Code
K12.33
Billable Status
Yes — Valid for Submission
Code Describes
Oral mucositis (ulcerative) due to radiation
Short Description
Oral mucositis (ulcerative) due to radiation
Same as the full description in the CMS dataset.
Parent Code
K12.3
Oral mucositis (ulcerative)

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK00-K14Diseases of oral cavity and salivary glands
CategoryK12Stomatitis and related lesions
This CodeK12.33Oral mucositis (ulcerative) due to radiation

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Use Additional Code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Mucositis(ulcerative)
      • mouth (oral) (oropharyngeal)
        • due to radiation

Clinical ClassificationClinical

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

CCSR DEN001
Any dental condition including traumatic injury
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG003
Diseases of mouth; excluding dental
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DEN002
Nontraumatic dental conditions
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Mouth Disorders

Your mouth is one of the most important parts of your body. It has many different functions. It allows you to:

Read the full article at MedlinePlus

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

Convert K12.33 to ICD-9-CMHistory

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

ICD-9-CM
528.01 Mucosits d/t antineo rx
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 K12.33Overview

Is K12.33 (Oral mucositis (ulcerative)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report oral mucositis (ulcerative) due to radiation on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K12.33 group to?

When oral mucositis (ulcerative) due to radiation is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, with relative weights from 0.7085 to 1.7168 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K12.33?

Under the General Equivalence Mappings, oral mucositis (ulcerative) due to radiation converts to ICD-9-CM 528.01 (mucosits d/t antineo rx). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.