Mouth Ulcers


Mouth ulcers (or apthous ulcers) are common, with as many as one in two of the population suffering from them, but the cause in many cases is unknown. They may occur on your tongue, on your soft palate, inside your cheeks or lips, and at the base of your gums. They differ from cold sores in that they occur in the soft tissues of your mouth and aren’t contagious. Conversely, cold sores rarely develop in the soft tissues of your mouth and are extremely contagious because they’re caused by the herpes virus.

How we get mouth ulcers

The cause of mouth ulcers in many people cannot be explained, but others may have caused by the following:-

Trauma or damage

A minor injury may trigger a mouth ulcer for example, over-zealous tooth-brushing, or eating or drinking something that is very hot as well as biting the inside of the mouth.


Normally mouth ulcers occurring as a symptom of a disease are associated with other symptoms.


Tingling or burning

This sensation may occur before the development of an ulcer.

A painful lesion(s)

Most mouth ulcers occur in crops of one to five with common being on the sides of the tongue and inside the lips and cheeks. They may be up to 5mm in diameter and have a white or yellowish centre with an inflamed, red outer edge.

Risk Factors


Minor injuries to the mucous membranes occur commonly in people who wear dentures (they may not fit properly) and people who wear braces or other orthodontic devices.

Food and Nutrition

A deficiency of vitamin B12, zinc, folic acid or iron may cause mouth ulcers and also lead to other symptoms involving the lips, tongue and oral mucosa. These kinds of deficiences are more likely to occur in people with diseases of the gastrointestinal tract which affect absorption of nutrients (e.g. ulcerative colitis). Mouth ulcers may also be caused by allergies to some foods.

Age, sex and family history

Mouth ulcers occur more between the ages of ten and forty and it is estimated that in one in three people suffering from mouth ulcers there is a family history of mouth ulcers. Women more commonly suffer from them and they often occur before the start of the menstrual period. Ulcers often occur less or even not at all during pregnancy, which indicates a hormonal involvement.

Reduced immune system function

People who are taking drugs which lower the effectiveness of their immune system (for example after transplantation, for the treatment of cancer or for auto-immune conditions such as rheumatoid arthritis or colitis) and people with HIV are more likely to get mouth ulcers. This is because the mouth normally contains a large number of micro-organisms, which provide a healthy environment in the mouth. But if the immune system is not functioning properly, the balance of these micro-organisms can change and this can cause problems, such as the development of mouth ulcers.

Blood Disorders

Rarely, mouth ulcers may be associated with disorders of the blood including anaemia and the abnormally low white cell count of leukaemia.

Oral Cancer

Oral cancers are more common in smokers. Oral cancer more commonly affects the lips but can affect the tongue.


These mainly occur when a mouth ulcer that is left untreated is infected by bacteria and this can lead to infection of the whole mouth or teeth.

When to seek medical advice

See your doctor if you experience mouth ulcers with any of the following.

  • Unusually large sores
  • Persistent sores, lasting three weeks or more
  • Pain that you can’t control with self-care measures
  • Difficulty drinking enough fluids
  • High fever with mouth ulcers
  • Diarrhoea
  • Weight loss
  • Involvement of other mucous membranes (e.g. genitalia)


Most ulcers usually heal within seven to ten days. Preparations on sale in pharmacies for the treatment of mouth ulcers can help to relieve the discomfort and pain and also reduce the risk of a bacterial infection.

Many over-the-counter preparations are not suitable for those who are pregnant or for children under two years of age and may not be suitable for other individuals, so it is always important to talk to your pharmacist when buying preparation for mouth ulcers over-the-counter.

The treatments available may contain several different ingredients but are formulated as gels, liquids, mouthwashes, pastilles or tablets.

Local anaesthetics (e.g. lignocaine and benzocaine)

These provide pain relief. They are most often included with antibacterials in either gels or pastilles. Gels may have to be re-applied to ulcers frequently as the salivary flow of the mouth tends to wash them away. Pastilles are better at providing longer pain relief if they can be held against the site of the ulcer with the tongue or gum, this may not be possible if there are several ulcers of the ulcers are in difficult to reach places.

Analgesic (e.g. choline salicylate)

This provides pain relief. It is most often included with antibacterials in gels. As suggested previously these gels may have to be re-applied to ulcers frequently.

Anti-bacterials (e.g. chlorhexidine gluconate, cetylpyridinium chloride, povidone-iodine)

These reduce the risk of bacterial infection of ulcers, the result of which can lead to increased discomfort and the delay of healing. They are included with other ingredients in gels and pastilles and can be found alone in many mouthwashes.

Anti-inflammatories (e.g. benzydamine and carbenoxolone)

These also provide pain relief.

Benzydamine is available as a mouthwash and is particularly useful when ulcers are in inaccessible areas or where there are several ulcers.

Carbenoxolone is available as an oral gel and can be applied in a thick layer to ulcers after meals and before going to bed.

Protective agents (e.g. polyvinylpyrrolidone (PVP) and carmellose)

PVP is available as mouthwash and it works by providing a protective lining over the mucous membranes and over the ulcers. This again is useful when ulcers are in inaccessible areas or there are several ulcers.

Carmellose is available as a paste and forms a protective mechanical barrier when applied to ulcers.

Brand name of preparations available and their ingredients

Preparations containing analgesics and antibacterials

Bonjela gel contains analgesic choline salicylate and antibacterial cetalkonium chloride.

Rinstead pastilles contain menthol, which has a soothing effect and antibacterial cetylpyridinium chloride.

Both provide pain relief and reduce the risk of bacterial infection of ulcers. Gels should be applied frequently, pastilles can be held by the tongue or gum to the site of the ulcer(s). They do not cause drowsiness.

Preparations containing local anaesthetics and antibacterials

Medijel gel contains local anaesthetic lignocaine and antibacterial aminacrine hydrochloride.

Anbesol liquid contains local anaesthetic lidocaine and antibacterials chlorocresol and cetylpyridinium chloride.

Rinstead gel contains local anaesthetic benzocaine and antibacterial chloroxylenol.

All provide pain relief due to the inclusion of the local anaesthetics and the anti-bacterials reduce the risk of bacterial infection of ulcers. They should be applied frequently, particularly after eating or drinking. They do not cause drowsiness.

Preparations containing anti-inflammatories

Difflam oral rinse contains anti-inflammatory benzydamine.

Carbosan gel contains anti-inflammatory carbenoxolone.

Both reduce pain due to the anti-inflammatory effect and a mouth wash is particularly useful when there are many ulcer sites. They should be used regularly, particularly after eating or drinking. They do not cause drowsiness.

Preparations containing protective agents

Aloclair mouth wash contains protective agent polyvinylpyrrolidine.

Orabase paste contains protective agent carmellose.

Both form a protective barrier over ulcers to reduce further irritation by foods and drinks. They should be used regularly, particularly after eating or drinking. They do not cause drowsiness.


Because mouth ulcers can recur, you may be able to reduce their frequency by addressing factors that seem to trigger them.
Watch what you eat

Avoid foods that seem to irritate your mouth. These may include acidic foods, nuts and certain spices.

Don’t chew and talk at the same time

You could cause minor trauma to the delicate lining of your mouth, triggering a mouth ulcer.

Follow good oral hygiene

Regular brushing after meals and flossing once a day can keep your mouth clean and free of foods that might trigger an ulcer. Using a soft brush may help you avoid irritation of mouth tissues.

Self Care

The following practices may provide temporary relief from mouth ulcers.

Watch what you eat

Avoid abrasive, acidic or spicy foods, which may increase the pain.

Use ice

Apply ice to your mouth ulcers or allow small ice cubes to slowly dissolve over the ulcers to ease the pain.

Take care when brushing teeth

Brush your teeth carefully using a very soft brush to avoid irritating the ulcers.

Use salt water
Rinse your mouth with salt water to help the ulcers heal.