We all have mouth ulcers occasionally. The medical term for them is aphthous ulcers. They are round, painful sores inside the mouth, which interfere with eating and toothbrushing because of the pain. The centre of the sore is white or greyish. Usually, eating spicy or salty foods is especially painful.
An unlucky 20% of the population suffer from mouth ulcers repeatedly. Usually the problem starts in childhood or adolescence and seems to get better in the 40s. Typically, the ulcers come in crops of one to five at a time. The mouth is remarkably good at healing, so the ulcers last for only a week or two. Then a few weeks later it may happen again.

Causes of Mouth Ulcers

Most mouth ulcer sufferers note that ulcers are more likely when they are feeling stressed or run-down – these were the top two causes reported to www.mouthulcers.org.

Although the cause of most mouth ulcers is unknown, accidental damage is a common reason. For example, biting the tongue or cheek lining by mistake, eating foods that are too hot, a sharp broken tooth, or wearing badly fitting dentures can all produce a mouth ulcer.

In 1 in 3 sufferers, it seems to run in the family because of an inherited tendency. A few people who constantly get mouth ulcers are anaemic or short of iron, folate or vitamin B12. Zinc deficiency, food hypersensitivity and general psychological stress have all been blamed for mouth ulcers, but specialists now think these are unlikely to be responsible. A few women find that mouth ulcers are more likely before their periods, so hormones might perhaps have an influence. Annoyingly, some people develop mouth ulcers after stopping smoking.

Repeated mouth ulcers can be part of several medical conditions (such as coeliac disease).and skin conditions. Though these disorders are unusual, you should see your doctor if you have mouth ulcers often.

Biphosphonate tablets (a bone-strengthening medication) can burn the inside of the mouth if you allow them to dissolve in the mouth rather than swallowing them whole with plenty of water.

Very rarely, a mouth ulcer can be cancerous. A cancerous ulcer does not heal, and is more common in older people, especially long-term smokers and drinkers. So, you should see your doctor if you have an ulcer that does not heal within 3 weeks. If your ulcer is painless, do not ignore it because cancerous ulcers may be pain-free.

What to Do about Mouth Ulcers

Unfortunately, there is no reliable way of preventing ordinary mouth ulcers.

  • You could try chlorhexidine gluconate mouth rinse, which you can buy in the UK from a pharmacy without a prescription. Use it twice daily.
  • There is some evidence that this may reduce the frequency and severity of recurrent mouth ulcers, but long-term use can stain the teeth.
  • Look for a toothpaste that does not contain sodium lauryl sulphate (SLS). One study showed that switching to a SLS-free toothpaste more than halved the likelihood of recurring mouth ulcers, but another study found no difference (Oral Disorders 1999;5:39–43).
  • Avoid spicy, acidic, salty or hard/abrasive foods (e.g. toast and crisps).
  • To avoid nutritional deficiencies, ensure that you eat a varied diet.
  • Pay attention to your oral hygiene.
  • Regular dental checks are important as they can help with sharp teeth or broken fillings that may trigger your mouth ulcers.
  • Additives in toothpastes, such as sodium lauryl sulphate, may aggravate your ulcers.

Any single ulcer that persists for longer than 3 weeks despite treatment should be examined by your dentist (or doctor) who may wish to refer you for a specialist opinion and possible biopsy.

There are various ways of relieving the pain, while waiting for the ulcer to heal itself.

  • Avoid spicy, salty or sour foods until the ulcer has healed.
  • Dissolve a tablet of soluble (dispersible) paracetamol in water and swirl it round your mouth before swallowing it.
  • Before eating, rinse your mouth with iced water. This may dull the pain, so that eating is more comfortable.
  • Use alcohol-free mouth wash.
  • Apply covering agents.
  • Buy a mouth ulcer liquid rinse or gel from a pharmacy. These contain an anaesthetic. Many people find the rinse easier to use than a gel, especially if they have several ulcers at the same time, and the rinse forms a protective barrier over the ulcer as well as relieving pain.
  • Some people find that warm (not hot) camomile tea is helpful. Swirl it round the mouth before drinking it.

What Your Dentist Can Do

Dentists are experts on all types of mouth problems, so your dentist will be able to give you general advice about mouth ulcers. Another reason to see your dentist is that trauma from a sharp tooth, a brace or ill-fitting dentures are common causes of mouth ulcers.

What Your Doctor Can Do

Your doctor can prescribe a corticosteroid paste. This is the best treatment for getting rid of ordinary mouth ulcers (aphthous ulcers), but of course it does not prevent them from occurring again. Apply it as soon as you suspect that an ulcer is forming. Dry the area with a tissue first, so that the paste sticks on.

Although ordinary aphthous ulcers are the most likely, there are other possibilities. Mouth ulcers can be part of several medical and skin conditions, so tell your doctor if you have any other symptoms, or if you have blisters or sores on any other part of your body. Your family physician may wish to check a blood sample for levels of iron, folate and vitamin B12. Of course, anyone with a mouth ulcer that does not go away in 3 weeks should see their doctor, because a persistent ulcer that refuses to heal could be cancerous.


First published on: embarrassingproblems.com
Reviewed and edited by: Dr Anna Cantlay
Last updated: October 2020

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