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What are mouth ulcers?

Ulcers are painful sores that appear inside the mouth. They are usually red or yellow. They are different from cold sores, which appear on the outer lips and are due to a virus.

What are the common causes of mouth ulcers?

Usually a single mouth ulcer is due to damage caused by say biting the cheek or tongue, sharp teeth, tooth brushing or poorly fitting dentures. These ulcers are called ‘traumatic ulcers’.

If you have a number of mouth ulcers the usual cause is ‘recurrent aphthous stomatitis’.

How do I know if I have a traumatic ulcer?

Traumatic ulcers are usually on their own, are next to the cause of the damage and go away once the source of the problem is removed.


What are the signs of recurrent aphthous stomatitis?


Recurrent aphthous stomatitis is a common problem and leads to repeated bouts of mouth ulcers in otherwise healthy children and young people. The cause is not known, but it is not infectious and is unlikely to be inherited.

Are there different types of recurrent mouth ulcers?


  • Minor ulcers are the most common. They can appear inside the cheeks, on the lips, tongue and gums and, more rarely, on the roof of the mouth. Most of these ulcers are the size of the top of a pencil and can sometimes come in clusters. You can get four to six at any one time.
  • Large ulcers are more severe and can longer to heal. Any ulcer that lasts longer than three weeks should be checked out by your dentist. Large ulcers may appear near the tonsils and can be very painful, especially when swallowing. You usually only get one at a time.
  • It is also possible to have up to 100 very small painful ulcers which last for one to two weeks.
  • However, these last two varieties are very rare.

You may get ulcers in other parts of the body such as your eyes or genital area. It is important to tell your dentist about this.


What are the less common causes of mouth ulcers?

Infections can cause mouth ulcers. Herpes simplex often leads to widespread mouth ulcers in children and some adults. Other less common viral and bacterial infections may cause mouth ulcers, but this is rare.

Mouth ulcers can be caused by anaemia and occasionally by other blood disorders and some skin or gastrointestinal diseases. Sometimes the mouth ulcers are the only sign of an underlying disease.


Can cancer cause mouth ulcers?

Cancer of the mouth can first appear as a mouth ulcer. The ulcers caused by mouth cancer are usually single and last a long time without any obvious local cause (for example a sharp tooth).

Any ulcer that lasts longer than three weeks should be looked at by your dentist.

Ulcers caused by cancer usually appear on or under the tongue, but may occasionally appear somewhere else in the mouth.

Cancer of the mouth is usually associated with heavy smoking and drinking. Doing both together greatly increases the risk.


Can I catch mouth ulcers?

Mouth ulcers cannot be caught by kissing or sharing drinks and utensils as they are not caused by an infection.


What types of treatment are there for mouth ulcers?

The treatment depends on the cause of the ulcers. Sometimes all that is needed is for a sharp tooth to be smoothed down or a denture adjusted, although some patients may need a variety of mouthwashes or tablets.


What should I do if I think I have mouth ulcers?

If an ulcer lasts more than a few weeks you should always ask your dentist or doctor for advice. They may be able to tell you the cause and provide treatment, or they may arrange further tests or refer you to a specialist if necessary.


How can I prevent mouth ulcers?


You may be able to reduce the risk of mouth ulcers by:

  • maintaining good oral hygiene
  • using high-quality toothbrushes (to reduce the risk of damage to your mouth)
  • eating a good diet which is rich in vitamins A, C and E and which includes foods such as fresh fruit and vegetables (to lessen the risk of mouth cancer)
  • regularly visiting your dentist.

Should I worry about my ulcers?

Most ulcers heal up on their own. However, if they don’t heal within three weeks you should visit your dentist. Your dentist will be able to examine your mouth to check that the problem is an ulcer and not something more serious such as mouth cancer.

If you suffer from ulcers that come and go often, you should visit your dentist or doctor to check that there is not an underlying medical cause.

Golden rules if you have mouth ulcers

Always see your dentist or doctor if:

  • The ulcer lasts for more than 3 weeks
  • You are unwell
  • The ulcers keep coming back.
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  • Holyhead Road
  • Llanfair Pwllgwyngyll
  • Anglesey
  • LL61 5TX

01248 787878

Get in touch with us

Why choose us?

  1. 1 Over 10 years experience boasting state-of-the-art technology
  2. 2 Dental Plans from £14.95 per month with access to exclusive discounts
  3. 3 Dental Implants that appear and function like a natural tooth
  4. 4 Most of our team are Welsh speakers, allowing you to speak in your language of choice