Aphthous Ulcer ICD-10-CM Codes | 2025

Are Aphthous Ulcer ICD-10-CM Codes billable?

Yes. The code K12.0 is valid and fully billable for documenting cases of aphthous ulcer, oral mucositis, or recurrent aphthous ulcer conditions in a patient. Healthcare providers can report this for initial and follow-up visits.

Clinical information

An aphthous ulcer—commonly known as a canker sore—is a form of oral mucosal lesion that appears as a painful, round or oval ulcerative lesion with a red border and yellow or white center. These oral cavity ulcers often present on the:

• Inner cheeks
• Gums
• Lips
• Tongue (often associated with tongue atrophic glossitis)
• Soft palate

They are non-contagious but can cause significant discomfort, especially during eating or speaking.

Common causes and contributing factors

The exact cause of recurrent aphthous ulcer formation remains unclear, but several underlying conditions and external factors are believed to contribute:

• Eating spicy foods or acidic foods
• Use of NSAIDs or other medications
• Emotional stress
• Mechanical trauma (e.g., braces or dental appliances)
• Deficiency in nutrients such as iron, folate, or B12
• Autoimmune conditions: Lupus, Crohn’s Disease, or AIDS
• Viral infections such as herpes simplex

In children, rare conditions like Bednar's aphthae may appear on the palate, often due to trauma.

Synonyms include:

• Aphthous ulcer of mouth
• Minor oral aphthous ulceration
• Recurrent aphthous ulcer
• Recurrent ulcer of mouth
• Recurrent oral aphthae
• Canker sore
• Recurrent canker sore
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