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ICD10

ICD-10 Code K12.3: Oral mucositis (ulcerative)

K12.3 is an ICD-10 diagnosis entry used to group records related to Oral mucositis (ulcerative). You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen. ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the digestive system (K00-K95).

What is this code?

ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Diseases of the digestive system (K00-K95).

When is it used?

  • May be used when a clinician documents oral mucositis (ulcerative) in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
  • This entry may represent a broader category rather than the most specific billable code.

Code hierarchy

chapter
11Diseases of the digestive system (K00-K95)
block
K00-K14Diseases of oral cavity and salivary glands
category
K12Stomatitis and related lesions
currentK12

Official coding notes

Inclusion terms
  • Mucositis (oral) (oropharyneal)
Excludes2 (may code together if documented)
  • gastrointestinal mucositis (ulcerative) (K92.81)
  • mucositis (ulcerative) of vagina and vulva (N76.81)
  • nasal mucositis (ulcerative) (J34.81)

Where you may see this code

You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.

Related specialists

GastroenterologistGeneral Physician

Coding guidelines

Compatibility

Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
K12.3
Replacement codes
K12.30 — Oral mucositis (ulcerative), unspecifiedK12.31 — Oral mucositis (ulcerative) due to antineoplastic therapyK12.32 — Oral mucositis (ulcerative) due to other drugsK12.33 — Oral mucositis (ulcerative) due to radiationK12.39 — Other oral mucositis (ulcerative)

Common synonyms

Oral mucositis (ulcerative)Oral mucositisOral mucositis ulcerative

Frequently asked questions

Code details

CodeK12.3
SystemICD10
Display nameOral mucositis (ulcerative)
ChapterDiseases of the digestive system (K00-K95)
BlockDiseases of oral cavity and salivary glands

Flags

BillableNo
Valid clinical useNo

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.