ICD-10-CM 2027
ICD-10 code for Canker
From the official ICD-10-CM alphabetic index entry “Canker (mouth) (sore)”. Page updated September 29, 2026.
About coding Canker
The ICD-10-CM code for Canker is K12.0 (Recurrent oral aphthae). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on K12.0.
Within K12 (stomatitis and related lesions), K12.0 is specifically for recurrent oral aphthae. Related codes cover other forms of stomatitis (K12.1), cellulitis and abscess of mouth (K12.2) and oral mucositis (ulcerative) (K12.3).
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 Canker codes (official index)
- rash A38.9 — Scarlet fever, uncomplicated
Common questions about Canker ICD-10 codes
What is the ICD-10 code for Canker?
- K12.0 — Recurrent oral aphthae. More specific codes apply when the documentation supports them: A38.9.
What is the ICD-10 code for rash canker?
- A38.9 — Scarlet fever, uncomplicated.
Is K12.0 billable?
- Yes. K12.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K12.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K12.0 as a principal diagnosis.
Is K12.0 a CC or MCC?
- No. K12.0 is neither a CC nor an MCC under MS-DRG v44.0.