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Mouth ulcers

Last updated on May 27, 2023

Mouth ulcersMouth ulcers are extremely common, affecting as many as one in five of the population, and are a recurrent problem in some people. They are classified as aphthous (minor or major) or herpetiform ulcers. Most cases (more than three quarters) are minor aphthous ulcers, which are self-limiting.

Ulcers may be due to a variety of causes including infection, trauma and drug allergy. However, occasionally mouth ulcers appear as a symptom of serious disease such as carcinoma. The pharmacist should be aware of the signs and characteristics that indicate more serious conditions.

What you need to know

Age, Child, adult, Nature of the ulcers, Size, appearance, location, number, Duration, Previous history, Other symptoms, Medication,  Significance of questions and answers


Patients may describe a history of recurrent ulceration, which began in childhood and has continued ever since. Minor aphthous ulcers are more common in women and occur most often between the ages of 10 and 40 years.

Nature of the ulcers

Minor aphthous ulcers usually occur in crops of one to five. The lesions may be up to 5 mm in diameter and appear as a white or yellowish centre with an inflamed red outer edge. Common sites are the tongue margin and inside the lips and cheeks. The ulcers tend to last from 5 to 14 days.

Other types of recurrent mouth ulcers include major aphthous and herpetiform. Major aphthous ulcers are uncommon, severe variants of the minor ones. The ulcers which may be as large as 30 mm in diameter can occur in crops of up to 10. Sites involved are the lips, cheeks, tongue, pharynx and palate. They are more common in sufferers of ulcerative colitis.

Herpetiform ulcers are more numerous, smaller and, in addition to the sites involved with aphthous ulcers, may affect the floor of the mouth and the gums. Table The three main types of aphthous ulcers summarises the features of the three main types of aphthous ulcers.

Table The three main types of aphthous ulcers.

Minor Major Herpetiform
80% of patients 10-12% of patients 8-10% of patients
2-10 mm in diameter (usually 5-6 mm) Usually over 10 mm in diameter; may be smaller 0.5-3.0 mm in diameter
Usually 1-5 mm in diameter Usually 10-20 mm in diameter or more 0.05-1.0 mm in diameter
Round or oval Round or oval Round or oval, coalesce to form irregular shape as they enlarge
Usually not very painful Prolonged and painful ulceration; may present patient with great problems – eating may become difficult May be very painful

Systemic conditions such as Behget’s syndrome and erythema multiforme may produce mouth ulcers, but other symptoms would generally be present.


Minor aphthous ulcers usually heal in less than 1 week; major aphthous ulcers take longer (10-30 days). Where herpetiform ulcers occur, fresh crops of ulcers tend to appear before the original crop has healed, which may lead patients to think that the ulceration is continuous.

Oral cancer

Any mouth ulcer that has persisted for longer than 3 weeks requires immediate referral to the dentist or doctor because an ulcer of such long duration may indicate serious pathology, such as carcinoma. Most oral cancers are squamous cell carcinomas, of which one in three affects the lip and one in four affects the tongue.

The development of a cancer may be preceded by a premalignant lesion, including erythroplasia (red) and leucoplakia (white) or a speckled leucoplakia. Squamous cell carcinoma may present as a single ulcer with a raised and indurated (firm or hardened) border. Common locations include the lateral border of the tongue, lips, floor of the mouth and gingiva. The key point to raise suspicion would be a lesion that had lasted for several weeks or longer. Oral cancer is more common in smokers than non-smokers.

Previous history

There is often a family history of mouth ulcers (estimated to be present in one in three cases). Minor aphthous ulcers often recur, with the same characteristic features of size, numbers, appearance and duration before healing. The appearance of these ulcers may follow trauma to the inside of the mouth or tongue, such as biting the inside of the cheek while chewing food. Episodes of ulceration generally recur after 1-4 months.

Ill-fitting dentures may produce ulceration and, if this is a suspected cause, the patient should be referred back to the dentist so that the dentures can be refitted. However, trauma is not always a feature of the history, and the cause of minor aphthous ulcers remains unclear despite extensive investigation.

In women, minor aphthous ulcers often precede the start of the menstrual period. The occurrence of ulcers may cease after pregnancy, suggesting hormonal involvement. Stress and emotional factors at work or home may precipitate a recurience or a delay in healing but do not seem to be causative.

Deficiency of iron, folate, zinc or vitamin B12 may be a contributory factor in aphthous ulcers and may also lead to glossitis (a condition where the tongue becomes sore, red and smooth) and angular stomatitis (where the corners of the mouth become sore, cracked and red).

Food allergy is occasionally the causative factor and it is worth enquiring whether the appearance of ulcers is associated with particular foods.

Other symptoms

The severe pain associated with major aphthous or herpetiform ulcers may mean that the patient finds it difficult to eat and, as a consequence, weight loss may occur. Weight loss would therefore be an indication for referral.

In most cases of recurrent mouth ulcers the disease eventually burns itself out over a period of several years. Occasionally, as in Behget’s syndrome, there is progression with involvement of sites other than the mouth. Most commonly, the vulva, vagina and eyes are affected, with genital ulceration and iritis.

Behcet’s syndrome can be confused with erythema multiforme, although in the latter there is usually a distinctive rash present on the skin. Erythema multiforme is sometimes precipitated by an infection or drugs (e.g. sulphonamides or barbiturates).

Mouth ulcers may be associated with inflammatory bowel disorders or with coeliac disease. Therefore, if persistent or recurrent diarrhoea is present, referral is essential. Patients reporting any of these symptoms should be referred to their doctor.

Rarely, ulcers may be associated with disorders of the blood including anaemia, abnormally low white cell count or leukaemia. It would be expected that in these situations there would be other signs of illness present and the sufferer would present directly to the doctor.


The pharmacist should establish the identity of any current medication, since mouth ulcers may be produced as a side-effect of drug therapy. Drugs that have been reported to cause the problem include aspirin and other non-steroidal anti-inflammatory drugs (non-steroidal anti-inflammatory drugs), cytotoxic drugs and sulphasalazine (sulfasalazine). Radiotherapy may also induce mouth ulcers. It is worth asking about herbal medicines because feverfew (used for migraine) can cause mouth ulcers.

It would also be useful to ask the patient about any treatments tried either previously or on this occasion and the degree of relief obtained. The pharmacist can then recommend an alternative product where appropriate.

When to refer

  • Duration of longer than 3 weeks
  • Associated weight loss
  • Involvement of other mucous membranes
  • Rash
  • Suspected adverse drug reaction
  • Diarrhea
  • Treatment timescale

If there is no improvement after 1 week, the patient should see the doctor.


Symptomatic treatment of minor aphthous ulcers can be recommended by the pharmacist and can relieve pain and reduce healing time. Active ingredients include antiseptics, corticosteroids and local anaesthetics. There is evidence from clinical trials to support use of topical corticosteroids and chlorhexidine mouthwash. Gels and liquids may be more accurately applied using a cotton bud or cotton wool, provided the ulcer is readily accessible. Mouthwashes can be useful where ulcers are difficult to reach.

Chlorhexidine gluconate mouthwash

There is some evidence that chlorhexidine mouthwash reduces duration and severity of ulceration. The rationale for the use of antibacterial agents in the treatment of mouth ulcers is that secondary bacterial infection frequently occurs. Such infection can increase discomfort and delay healing. Chlorhexidine helps to prevent secondary bacterial infection but it does not prevent recurrence. It has a bitter taste and is available in peppermint as well as standard flavour.

Regular use can stain teeth brown – an effect that is not usually permanent. Advising the patient to brush the teeth before using the mouthwash can reduce staining. The mouth should then be well rinsed with water as chlorhexidine can be inactivated by some toothpaste ingredients. The mouthwash should be used twice a day, rinsing 10 mL in the mouth for 1 min and continued for 48 h after symptoms have gone.

Topical corticosteroids

Hydrocortisone and triamcinolone act locally on the ulcer to reduce inflammation and pain and to shorten healing time. The former is used as pellets, the latter as a protective paste. To exert its effect a pellet must be held in close proximity to the ulcer until dissolved. This can be difficult when the ulcer is in an inaccessible spot. One pellet is used four times a day.

The pharmacist should explain that the pellets should not be sucked, but dissolved in contact with the ulcer. These treatments are best used as early as possible. Before an ulcer appears, the affected area feels sensitive and tingling – the prodromal phase – and treatment should start then. They should be applied three to four times daily. They have no effect on recurrence, but should be restarted at the first signs of a new outbreak.

Local analgesics

Benzydamine mouthwash or spray and choline salicylate dental gel are short acting but can be useful in very painful major ulcers. The mouthwash is used by rinsing 15 mL in the mouth three times a day.

Numbness, tingling and stinging can occur with benzydamine. Diluting the mouthwash with the same amount of water before use can reduce stinging. The mouthwash is not licensed for use in children under 12. Benzydamine spray is used as four sprays onto the affected area three times a day. Although aspirin is no longer recommended for children under 16 years because of possible links with Reye’s syndrome, choline salicylate dental gel produces low levels of salicylate and can therefore be used in children.

Local anaesthetics (e.g. lidocaine (lignocaine) and benzocaine)

Local anaesthetic gels are often requested by patients. Although they are effective in producing temporary pain relief, maintenance of gels and liquids in contact with the ulcer surface is difficult. Reapplication of the preparation may be done when necessary. Tablets and pastilles can be kept in contact with the ulcer by the tongue and can be of value when just one or two ulcers are present. Any preparation containing a local anaesthetic becomes difficult to use when the lesions are located in inaccessible parts of the mouth.

Both lidocaine and benzocaine have been reported to produce sensitisation, but cross sensitivity seems to be rare, probably because the two agents are from different chemical groupings. Thus, if a patient has experienced a reaction to one agent in the past, the alternative could be tried.

Mouth ulcers in practice

Case 1

Anthony Jarvis, a man in his early fifties, asks you to recommend something for painful mouth ulcers. On questioning, he tells you that he has two ulcers at the moment and has occasionally suffered from the problem over many years. Usually he gets one or two ulcers inside the cheek or lips and they last for about 1 week. Mr Jarvis is not taking any medicines and has no other symptoms.

You ask to see the lesions and note that there are two small white patches, each with an angry-looking red border. One ulcer is located on the edge of the tongue and the other inside the cheek. Mr Jarvis cannot remember any trauma or injury to the mouth and has had the ulcers for a couple of days. He tells you that he has used pain-killing gels in the past and they have provided some relief.

The pharmacist’s view

From what he has told you, it would be reasonable to assume that Mr Jarvis suffers from recurrent minor aphthous ulcers. Treatment with hydrocortisone pellets (one pellet dissolved in contact with the ulcers four times a day), with triamcinolone in carmellose dental paste, or with a local anaesthetic or analgesic gel applied when needed, would help to relieve the discomfort until the ulcers healed. Mr Jarvis should see his doctor if the ulcers have not healed within 3 weeks.

The doctor’s view

Mr Jarvis is most likely suffering from recurrent aphthous ulceration. As always, it is worthwhile enquiring about his general health, checking, in particular, that he does not have a recurrent bowel upset or weight loss. These ulcers can be helped by a topical steroid preparation.

Case 2

One of your counter assistants asks you to recommend a strong treatment for mouth ulcers for a woman who has already tried several treatments. The woman tells you that she has a troublesome ulcer that has persisted for a few weeks. She has used some pastilles containing a local anaesthetic and an antiseptic mouthwash but with no improvement.

The pharmacist’s view

This woman should be advised to see her doctor for further investigation. The ulcer has been present for several weeks, with no sign of improvement, suggesting the possibility of a serious cause.

The doctor’s view

Referral is correct. It is likely that the doctor will refer her to an oral surgeon for further assessment and probable biopsy as the ulcer could be malignant. Cancer of the mouth accounts for approximately 2% of all cancers of the body in Britain. It is most common after the sixth decade and is more common in men, especially pipe or cigar smokers. Cancer of the mouth is most often found on the tongue or lower lip. It may be painless initially.

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