Mouth Ulcers (Aphthous Ulcers/Stomatitis): Causes and What to Do

Mouth ulcers (aphthous ulcers) are small, often painful sores that form on the soft tissues of the mouth — the inside of the cheeks, under the tongue or on the gums; in most cases they are harmless and heal on their own within 1–2 weeks. They are not contagious and are usually not a sign of a serious illness. However, if the ulcers recur frequently, are large or do not clear up within two weeks, you should see a dentist.

What is a mouth ulcer (aphthous ulcer)?

An aphthous ulcer (aphthous stomatitis) is a superficial sore on the lining of the mouth with a whitish-yellow centre and red edges. They should not be confused with a cold sore (herpes), which appears on the lip and is contagious — a cold sore is usually on the outside of the lip, whereas an aphthous ulcer is located inside the mouth.

Causes of mouth ulcers

The exact cause of aphthous ulcers is not always known, but the following factors can be triggers:

• Minor trauma: biting, vigorous brushing, a sharp tooth edge or friction from an orthodontic appliance.
• Stress and fatigue.
• Certain food sensitivities: acidic, spicy or very hot foods.
• Vitamin/mineral deficiency: iron, B12, folic acid.
• Hormonal changes.
• Certain systemic conditions (in recurrent and severe cases).

What can you do at home?

Most aphthous ulcers heal without treatment, but the discomfort can be eased:

• Temporarily avoid acidic, salty, spicy and very hot foods.
• Use a soft toothbrush and try not to irritate the ulcer.
• Gently rinsing with warm salt water can bring relief.
• Drink plenty of fluids and keep up your oral hygiene.
• Over-the-counter topical soothing gels may help — consult your pharmacist or dentist before use.

These are general recommendations; the specific treatment approach is determined after an individual examination.

When should you see a dentist?

It is advisable to contact your dentist or doctor in the following cases:

• The ulcer does not heal within more than two weeks.
• The ulcers are unusually large or numerous.
• The aphthous ulcers recur frequently.
• There is a high temperature, difficulty swallowing or severe pain.
• The edges of the ulcer become hard or its appearance changes.

Any mouth ulcer that does not clear up within two weeks should be assessed by a specialist — this is simply a precaution and should not be a cause for worry.

Prevention

• Gentle brushing and good oral hygiene reduce sources of friction.
• If you have sharp tooth edges or a poorly fitting denture/appliance, have them checked by your dentist.
• Noting and limiting trigger foods can reduce recurrences.
• A balanced diet can prevent cases linked to vitamin deficiency.

Questions and Answers (FAQ)

Are mouth ulcers contagious? Ordinary aphthous ulcers (aphthous stomatitis) are not contagious. However, a cold sore (herpes) on the lip is a virus and is contagious. It is important not to confuse the two; if in doubt, see your dentist.

How long does an aphthous ulcer take to heal? Most small aphthous ulcers heal on their own within 7–14 days and leave no scar. An ulcer that does not clear up within two weeks should be assessed by a specialist.

How can the pain of a mouth ulcer be reduced? Avoiding acidic and spicy foods, gentle brushing, warm salt-water rinses and the use of pharmacy gels can bring relief. If the pain is severe or persistent, consult your dentist.

What should you do if you get mouth ulcers frequently? Recurrent aphthous ulcers may be linked to vitamin deficiency, stress or other factors. In this case it is advisable to see a doctor to identify the cause.

---

Clinical note: This article is for general information only and does not replace individual medical advice. To have persistent or recurrent mouth ulcers assessed, book an appointment.

Sources: Peer-reviewed dental literature on diseases of the oral mucosa. Clinical content is based on Dr. Minaya's experience.