ICD-10 Code K12.0 – Recurrent oral aphthae (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K12.0 – Recurrent oral aphthae
What it is
K12.0 identifies recurrent oral aphthae, also called recurrent aphthous ulcers or canker sores. It refers to repeated, painful ulcers in the mouth that are not caused by trauma or a known infection.
Clinical signs
Typical findings include one or more shallow, round or oval ulcers with a sore base and a surrounding red halo. Clinical features vary; refer to documentation if the pattern, location, or recurrence is unclear.
When to use this code
Use K12.0 when the record documents recurrent aphthous ulcers, recurrent canker sores, or similar wording affecting the oral mucosa. You may also use it when the clinician clearly identifies recurrent oral aphthae as the diagnosis. Check documentation if the chart only mentions mouth pain, oral ulcer, or stomatitis without recurrence.
Do not use for
Do not use this code for traumatic mouth ulcers, herpetic lesions, or oral ulcers linked to another confirmed cause. If the record does not specify recurrence or aphthous type, check documentation.
Coding tip
Code K12.0 only when recurrence is documented; a single unspecified mouth ulcer usually needs a different code.