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Recurrent Aphthous Stomatitis (recurrent mouth ulcers)

What is Recurrent Aphthous Stomatitis (RAS)?

RAS consists of recurrent bouts of one or more painful, rounded or ovoid ulcers. Most aphthous ulcers last for 10-14 days. It is a common mouth condition affecting up to 20% of the population at any given time. The severity and frequency of RAS tends to decrease with age.

RAS is classified into three types:

  • Minor

  • Major

  • Herpetiform

Minor ulcers are the most common type affecting the majority (80%) of people who suffer from mouth ulcers. Minor ulcers occur in crops of about 1 to 5 at a given time and are usually 10mm or less in diameter.


These usually appear inside the lips and cheeks, on the tongue and sometimes the floor of the mouth. The ulcers tend to last between 10-14 days and heal without scarring


Major ulcers are less common and affect 10-15% of patients with RAS. Major ulcers tend to be larger and typically greater than 10mm in diameter. They can occur singly or 2-3 can appear at a time anywhere in the mouth. If the soft palate is involved, swallowing can be difficult. The ulcers may last up to 3 months and some of the larger ulcers leave a scar when healed.

Herpetiform ulcers are the least common type affecting 5-10% of cases. The ulcers are small (1-2mm in diameter) and can occur in clusters of more than 20 at a time which can merge to give larger ulcers. They tend to occur in the front of the mouth particularly under the tongue and on the edges of the tongue. These tend to heal within two weeks without scarring. Despite their name, they are not caused by a herpes virus.


What causes recurrent aphthous stomatitis?

The cause is unknown but there is likely to be an immunological factor involved. There are a number of underlying or precipitating factors which include anaemia, vitamin deficiencies, stress and trauma from sharp teeth, dental braces/fillings or a tooth brush. Some people who give up smoking develop recurrent mouth ulcers and the reason for this is unclear. Occasionally, RAS can be part of a more widespread disease affecting other parts of the body (eg Behçet's disease). Recurrent mouth ulcers are not thought to be infectious.

Is recurrent aphthous stomatitis hereditary?

Nearly half the people who suffer from mouth ulcers have a close relative with the same problem

What does recurrent aphthous stomatitis look like?

Recurrent aphthous stomatitis consists of round or oval shaped ulcers with an area of surrounding redness. The base of an ulcer is typically grey/yellow in colour. Size varies according to the type of ulcer and this may range from a few millimetres in diameter to greater than one centimetre.

What are the symptoms of recurrent aphthous stomatitis?

The main complaint is pain. This can be made worse by hot, salty, spicy or hard/abrasive food. Eating and drinking can therefore become difficult. Depending on the site of ulcers, speech can also be affected. The ulcers occur in recurrent bouts, heal and reoccur with varying time intervals. A few people are never free from ulcers.

How is recurrent aphthous stomatitis diagnosed?

The history and clinical appearance of the ulcers are usually sufficient to confirm the diagnosis of RAS. Blood tests are often arranged to check for any underlying cause. A biopsy is occasionally required to rule out other causes of mouth ulceration.

Can recurrent aphthous stomatitis be cured?

There is currently no cure for RAS unless an underlying cause is found and corrected. Treatment aims to relieve the painful symptoms associated with RAS. The frequency and severity of RAS tends to decrease with age.

How can recurrent aphthous stomatitis be treated?

Treatment for RAS aims to relieve discomfort, prevent or reduce secondary infection and encourage healing.

Topical corticosteroids are the main treatment for RAS. They can be applied locally to the mouth and are effective for most patients. These are available as mouthwashes, sprays, and small dissolvable pellets.

Anaesthetic (analgesic) mouthwashes, sprays or ‘over-the-counter’ sugar free throat lozenges can be used if your mouth becomes sore and are particularly helpful if used before meals.

Use of an antiseptic alcohol-free mouthwash, spray or gel (e.g. chlorhexidine gluconate) may be recommended to help reduce any secondary infection and control plaque levels on teeth if toothbrushing is difficult or uncomfortable. Tetracycline mouthwashes may be of value for some types of RAS.

Covering agents work by forming a mechanical barrier against secondary infection and further mechanical irritation. These are available as pastes and soluble pellets for application to ulcers.

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Modern Dentistry

Level 1 City Walk Centre

City Walk



ACT 2601

Above King O'Malleys Pub

Work: 02 6247 8400

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Modern Dentistry

Monday - 8:30 am - 5:30 pm

Tuesday - 8:30 am - 5:00 pm

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