ICD-10-CM 2027
ICD-10 code for mouth mucositis
From the official ICD-10-CM alphabetic index entry “Mucositis (ulcerative) › mouth (oral) (oropharyngeal)”. Page updated September 29, 2026.
About coding mouth mucositis
The ICD-10-CM code for mouth mucositis is K12.30 (Oral mucositis (ulcerative), unspecified). The official index lists 5 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on K12.30.
Within K12.3, choose K12.30 (unspecified) only when documentation doesn't support a more specific option: due to antineoplastic therapy (K12.31), due to other drugs (K12.32), due to radiation (K12.33) and other oral mucositis (ulcerative) (K12.39).
Use an additional code to identify: alcohol abuse and dependence (F10.-), exposure to environmental tobacco smoke (Z77.22), exposure to tobacco smoke in the perinatal period (P96.81), history of tobacco dependence (Z87.891), occupational exposure to environmental tobacco smoke (Z57.31) and 2 more.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific mouth mucositis codes (official index)
- due to antineoplastic therapy K12.31 — Oral mucositis (ulcerative) due to antineoplastic therapy
- due to drugs NEC K12.32 — Oral mucositis (ulcerative) due to other drugs
- due to radiation K12.33 — Oral mucositis (ulcerative) due to radiation
- specified NEC K12.39 — Other oral mucositis (ulcerative)
- viral K12.39 — Other oral mucositis (ulcerative)
Common questions about mouth mucositis ICD-10 codes
What is the ICD-10 code for mouth mucositis?
- K12.30 — Oral mucositis (ulcerative), unspecified. More specific codes apply when the documentation supports them: K12.31, K12.32, K12.33, K12.39 and others below.
What is the ICD-10 code for viral mouth mucositis?
- K12.39 — Other oral mucositis (ulcerative).
Is K12.30 billable?
- Yes. K12.30 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K12.30 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K12.30 as a principal diagnosis.
Is K12.30 a CC or MCC?
- No. K12.30 is neither a CC nor an MCC under MS-DRG v44.0.