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Mouth ulcers

There are a number of causes and types of mouth ulcers. Aphthous mouth ulcers are the most common and recur from time to time. The ulcer(s) will usually go without treatment in 10-14 days. Mouthwashes and lozenges may ease the pain and may help the ulcers to heal more quickly.

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What are mouth ulcers?

Mouth ulcers are painful sores that can occur anywhere inside the mouth. This leaflet is about the most common type of mouth ulcers, which are aphthous mouth ulcers. At least 1 in 5 people can develop aphthous mouth ulcers at some stage in their lives. Women are affected more often than men.

There are three types:

  • Minor aphthous mouth ulcers are the most common (8 in 10 cases). They are small, round, or oval and are less than 10 mm across. They look pale yellow but the area around them may look swollen and red. Only one ulcer may develop but up to five may appear at the same time. Each ulcer lasts 7-10 days and then goes without leaving a scar. They are not usually very painful.

  • Major aphthous mouth ulcers occur in about 1 in 10 cases. They tend to be 10 mm or larger across. Usually only one or two appear at a time. Each ulcer lasts from two weeks to several months but will heal leaving a scar. They can be very painful and eating may become difficult.

  • Herpetiform mouth ulcers occur in about 1 in 10 cases. These are tiny pinhead-sized ulcers, about 1-2 mm across. Multiple ulcers occur at the same time but some may join together and form irregular shapes. Each ulcer lasts one week to two months. Despite the name, they have nothing to do with herpes or the herpes virus.

Aphthous mouth ulcers usually first occur between the ages of 10 and 40 years. They then come back (recur) but there can be days, weeks, months, or years between each bout of ulcers. The ulcers tend to recur less often as you become older. In many cases, they eventually stop coming back. Some people feel a burning in part(s) of the mouth for a day or so before an ulcer appears.

What causes aphthous mouth ulcers?

The cause is not known. They are not infectious and you cannot 'catch' aphthous mouth ulcers. In most cases, the ulcers develop for no apparent reason in people who are healthy.

In some cases the ulcers are related to other factors or diseases. These include:

  • Injury - such as badly fitting dentures, a graze from a harsh toothbrush, etc.

  • Changes in hormone levels. Some women find that mouth ulcers occur just before their period. In some women, the ulcers only develop after the menopause.

  • Stopping smoking - some people find they develop ulcers only after stopping smoking.

  • A lack of iron, or a lack of certain vitamins (such as vitamin B12 and folic acid) may be a factor in some cases.

  • Rarely, a food allergy may be the cause.

  • Mouth ulcers run in some families. So, a genetic factor may play a part in some cases.

  • Stress or anxiety is said to trigger aphthous mouth ulcers in some people.

  • Some medications can cause mouth ulcers. Medication can cause mouth ulcers in various ways and may not necessarily cause the aphthous type of ulcer. Examples of medicines that can cause mouth ulcers are:

Mouth ulcers are more common in people with certain conditions - for example, Crohn's disease, coeliac disease, HIV infection and Behçet's disease. However, these ulcers are not the aphthous type.

Symptoms in addition to mouth ulcers

You should inform your doctor if you have any other symptoms in addition to the mouth ulcers. Other important symptoms would include skin or genital ulcers or joint pains and inflammation. Sometimes a blood test or other investigations are advised if other causes of mouth ulcers are suspected.

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Aphthous mouth ulcers management

Treatment aims to ease the pain when ulcers occur and to help them to heal as quickly as possible. There is no treatment that prevents aphthous mouth ulcers from coming back (recurring).

No treatment may be needed

The pain is often mild, particularly with the common 'minor' type of aphthous ulcer. Each bout of ulcers will go without treatment.

General measures include

  • Avoiding spicy foods, acidic fruit drinks and very salty foods (such as crisps) which can make the pain and stinging worse.

  • Using a straw to drink, to avoid the liquids touching ulcers in the front of the mouth. (Note: do not drink hot drinks with a straw, as you may burn your throat.)

  • Using a very soft toothbrush. See a dentist if you have badly fitting dentures.

  • If you suspect a medication is causing the ulcers then a change may be possible. For example, if you are using oral nicotine replacement therapy (nicotine gum or lozenges), it may help to use a different type instead such as patches or nasal spray.

  • Salt (saline) mouthwashes. Dissolve half a teaspoon of salt in a glassful of warm water, swish around your mouth and spit it out. This can be done as often as needed and may be soothing. Do not swallow the salt mouthwash.

Some medicines may ease your symptoms from the mouth ulcers

  • Chlorhexidine mouthwash (Corsodyl® or Chlorohex®) may reduce the pain. It may also help mouth ulcers to heal more quickly. It helps to prevent mouth ulcers from becoming infected. Unfortunately, it does not reduce the number of new ulcers. Chlorhexidine mouthwash is usually used twice a day. It may stain teeth brown if you use it regularly. However, the stain is not usually permanent and can be reduced by avoiding drinks that contain tannin (such as tea, coffee, or red wine) and by brushing teeth before use. Rinse your mouth well after you brush your teeth, as some ingredients in toothpaste can inactivate chlorhexidine.

  • Steroid lozenges (Corlan® pellets) may also reduce the pain and may help mouth ulcers to heal more quickly. By using your tongue you can keep a lozenge in contact with an ulcer until the lozenge dissolves. A steroid lozenge works best the sooner it is started once an ulcer erupts. If used early, it may 'nip it in the bud' and prevent an ulcer from fully erupting. The usual dose is one lozenge, four times a day, until the ulcer goes. Use for no more than five days at a time.

  • Soothing protective pastes. These products, such as Orabase®, help to cover the ulcer temporarily to protect it.

  • A painkilling oral rinse, gel, or mouth spray may help to ease pain. The effect of these painkilling medicines is unfortunately short-lived. These can be bought at pharmacies. For all these products, follow the directions in the packet very carefully. Examples include:

    • Benzydamine spray or mouthwash (Difflam®)

    • Products containing a temporary numbing agent (local anaesthetic) called lidocaine.

    • Choline salicylate gel (Bonjela®). The adult form of Bonjela® should not be used in children under the age of 16 due to a potential risk of Reye's syndrome if it is overused. This is the same reason why aspirin cannot be used in children too. Bonjela® products for children no longer contain choline salicylate and have been reformulated with lidocaine.

Other treatments for mouth ulcers

You can buy all of the treatments listed above from pharmacies, without a prescription. Your doctor may suggest trying other treatments if the above do not help or where the pain and ulceration are severe. Examples include:

  • Painkilling tablets.

  • Steroid inhalers such as beclometasone, usually used for asthma, can be helpful when sprayed onto the lining of the mouth.

  • A soluble tablet containing the steroid betamethasone can be dissolved in water and used as a mouthwash.

  • A course of steroid tablets.

  • A course of an antibiotic such as doxycycline.

Occasionally using steroid preparations in this way can give you thrush in the mouth as a side-effect.

When should I consult a doctor about mouth ulcers?

Aphthous mouth ulcers can be painful and are often a nuisance but are not serious. Occasionally a mouth ulcer can become secondarily infected with germs (bacteria). In this case you may notice increased pain or redness, or you may be feeling unwell with a high temperature (fever). Secondary bacterial infections are not common but may need treatment with antibiotic medicines.

Remember, not all mouth ulcers are aphthous ulcers. Other types of ulcer can occur in the mouth and mouth ulcers can be a sign of an underlying illness or disease.

Important: cancer of the mouth can sometimes start as an unusual mouth ulcer that does not heal. You should see a doctor or dentist if you have a mouth ulcer that has lasted for more than three weeks without sign of healing, or is different in any way. This is especially important if you are a smoker. Your GP or dentist may refer you urgently to a specialist. A small sample (biopsy) of the ulcer may be taken in clinic and examined, to exclude cancer.

Further reading and references

Article History

The information on this page is written and peer reviewed by qualified clinicians.

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