← All explanationsAphthous ulcers

What are those small, painful sores in the mouth?

Aphthous ulcers are localised painful breaks in the oral lining, often with a pale centre and red border. They can recur. Not every sore is an aphthous ulcer; unusual or persistent changes should be examined.

For dental trainees & teams

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A small break in the oral lining

Aphthous ulcers often occur on movable oral lining. Even a small sore can be painful when eating or speaking.

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Not all mouth ulcers are the same

Irritation, injury and other conditions can look similar. Recurrent symptoms are assessed through their pattern and examination.

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Pay attention to duration and change

Small aphthous ulcers often heal in one to two weeks. Any sore still present after three weeks should be examined by a doctor or dentist.

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At a glance

What are aphthous ulcers?

Localised, often painful breaks in the oral lining.

How long can they last?

Small ulcers often heal within one to two weeks; other types may last longer.

When should they be examined?

For unusual or severe symptoms, and if any sore remains after three weeks.

Knowledge in motion

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Short film (German): What are those small, painful sores in the mouth?

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Often confused

Aphthous ulcer or cold sore?

Aphthous ulcers are not a herpes infection. Location, clinical course and examination help distinguish them.

Quick answers

Are aphthous ulcers contagious?

Typical aphthous ulcers are not contagious. This distinguishes them from some other oral conditions.

When should I seek earlier advice?

For very severe, frequent or unusual symptoms, or difficulty eating or drinking.

Does a white spot definitely mean an aphthous ulcer?

No. Appearance alone is not enough. Persistent or changing areas particularly need examination.

At the practice

For your consultation

A question to discuss with Dr. med. dent. Niusha Barahmand Pour:

Does the pattern fit aphthous ulcers, or does this area need a different assessment?

Symptoms and examination findings provide the basis for personal advice.

Persistent or unusual sores can be assessed by a dentist.

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Meet Dr. med. dent. Niusha Barahmand Pour

Learning for dental trainees & teamsUnderstand clinical terms and build your knowledge

Build on the simple explanation with clinical terms, key distinctions and a knowledge question.

Ulcer: A localised defect in the mucosal surface.
Recurrence: The return of a change that had previously resolved.
Minor aphthous ulcer: The smaller, common type of aphthous ulcer.

Know the difference

Typical aphthous ulcers are not herpes blisters and are not contagious. Similar changes can have other causes.

Knowledge questionWhich statement about assessment is correct?

This question supports learning. It does not assess personal symptoms.

A sore still present after three weeks should be examined.
Every pale mucosal area is definitely an aphthous ulcer.
Lack of pain rules out any need to assess a persistent area.

Show answer and explanation

A sore still present after three weeks should be examined.

Duration is an important clue. Unusual or severe symptoms should be assessed earlier.

Sources for further learning

Sources and context

Editorial research: 23 October 2026. This explanation covers general principles and does not replace a personal examination. Suitable treatment is discussed following individual assessment.