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Problems in the mouth

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find one of our health articles more useful.

This article is a general overview of a large topic, with links to other resources to allow further enquiry.

The differential diagnoses for the clinical scenarios presented are far from complete and other diagnoses may need to be considered, depending upon the specific details of a patient's presentation. It should, however, be useful as a quick reference diagnosis guide to the conditions seen in primary care that commonly cause oral problems.

Where there is doubt as to the nature of an oral pathology, seek further advice from a dental general practitioner, oral physician, oral surgeon, or ENT specialist. If you suspect that the oral problems may relate to systemic disease, refer to a general physician or the relevant speciality - eg, immunology.

Referral of patients with mouth ulcers

It is important not to miss a diagnosis of oral cancer in its early stages. See the separate Cancers of the Oral Cavity article.

Referral should be to an oral medicine department or to an oral and maxillofacial department.

Refer urgently:

  • If there is suspected malignancy (urgently): persistent symptoms (>3 weeks), unexplained bleeding, painful or swollen red or white patches.

Refer non-urgently:

  • If the patches are not painful, not swollen or not bleeding.

  • If there is a suspected underlying cause for aphthous-like ulcers.

  • If ulceration is especially disabling, painful or recurrent (despite a benign diagnosis).

NB: if there is a localised dental cause for the ulceration - refer to a dentist.

'Soreness' in the mouth is usually due to mucosal inflammation and/or ulcer formation. Mouth ulcers are extremely common and have a number of causes.

Continue reading below

Causes of mouth ulcers

For more detail see the separate Oral Ulceration article.

Aphthous ulcers

  • These are also referred to as canker sores, aphthous stomatitis, recurrent aphthous stomatitis (RAS), recurrent oral ulceration (ROU).

  • This condition tends to start in childhood or adolescence. There are recurrent small, round or ovoid ulcers with circumscribed margins, erythematous haloes and yellow or grey floors.

  • They affect at least 20% of the population and their natural course is one of eventual remission. They are often recurrent.1

Herpetic disease

Primary infection of herpes simplex virus type 1 (HSV-1) tends to occur in children under 5 years old. Infection occurs through intimate contact (eg, saliva) and viral shedding goes on from 4-60 hours following onset of symptoms (incubation period is 3-7 days). It may well be asymptomatic but patients who do present tend to do so with gingivostomatitis in children and as pharyngotonsillitis or a mononucleosis (glandular fever) type of illness in adults. There may be prodromal symptoms including fever, nausea, malaise, headache and irritability. Symptoms generally last for one to two weeks. This self-limiting condition can be adequately managed symptomatically with:

  • Analgesia (eg, paracetamol).

  • Good fluid intake.

  • Avoidance of salty or acidic foods.

  • Topical benzydamine, which may be helpful for pain relief.

  • Chlorhexidine mouthwash, which should minimise secondary infection.

  • Lip barrier preparations (eg, Vaseline®) which can be helpful.

Steps should be taken to minimise transmission:

  • Avoid touching the lesions - if this is necessary, such as after applying lip cream, wash hands afterwards.

  • Avoid kissing and oral sex until the lesions have healed.

  • Avoid sharing items which come into contact with the lesions.

  • If children are well, they do not need to be excluded from school or nursery.

Oral antivirals should be considered for immunocompetent individuals with severe gingivostomatitis. They are indicated within five days of the start of the episode, while new lesions are still forming, or if systemic symptoms persist.3

Specialist advice or referral is appropriate for:

  • Immunocompromised patients.

  • Pregnant patients.

  • If ulcers do not heal within 14 days.

  • Patients with frequent episodes (eg, more than six episodes a year).

  • Those with oral herpes simplex associated with recurrent erythema multiforme.

Admission should be considered for:

  • Patients at risk of dehydration where there is a risk of dehydration.

  • Immunocompromised patients with severe lesions.

  • Patients with suspected serious complications such as tracheobronchitis, pneumonia, oesophagitis, meningitis or encephalitis.3

Cold sores

This is the reactivation of latent HSV-1 which has remained dormant in the trigeminal ganglion. Cold sores are common and result in recurring symptoms in 20-40% of young adults who are seropositive for HSV-1.

  • This is usually a self-limiting condition (7-10 days) which can be managed symptomatically as with gingivostomatitis (above), with the same precautions needed to minimise the risk of transmission.

  • Topical antiviral treatment is widely available and may affect the course of the current episode if applied in the prodromal phase but preparations do not cure the patient or prevent further episodes.4 Prophylactic use is ineffective.

  • Consider seeking specialist advice, referral or admission using the same criteria as gingivostomatitis above.

Oral candidiasis5

This is a fungal infection of the oral mucosa, usually caused by Candida albicans, or sometimes by other Candida spp. Factors predisposing to oral candidiasis:


  • Pain - may make eating and drinking difficult.

  • Altered sense of taste - sometimes.

  • May be asymptomatic.

There are several clinical forms of oral candidiasis.

Other causes of sore mouth

Burning mouth syndrome (BMS)6

This idiopathic condition is characterised by a burning sensation in the tongue or other parts of the mouth in the absence of medical or dental causes.

  • Exclude local and systemic factors (such as xerostomia, infections, allergies, ill-fitting dentures, hypersensitivity reactions and hormone and vitamin deficiencies) before diagnosing BMS.

  • Dryness and taste disturbance are also often present.

  • Symptoms are sometimes relieved by eating and drinking (unlike mouth ulcers, which are more painful on eating).

  • It is more common in older adults (past middle age).

  • The cause is unclear - it may be a form of neuropathy.

  • Treatment and management of this condition are very difficult.7 Although not accompanied by evident organic changes, BMS can significantly reduce the quality of life for these patients.

Geographic tongue (benign migratory glossitis)

This is a common idiopathic condition affecting around 2-3% of the general population8 :

  • It presents with map-like red areas (hence its name) of atrophy of filiform tongue papillae. The areas and patterns may change rapidly (over hours). The tongue is often fissured.

  • Lesions may be asymptomatic but can cause soreness.

  • The cause is unknown.

  • There is debate regarding whether geographic tongue may be an oral manifestation of psoriasis.9

  • Diagnosis is based on the appearance. No treatment is necessary.

Continue reading below

Children's mouth problems

Causes of sore mouth or mouth ulcers to consider in children are as follows.

  • Dental disease.

  • Kawasaki disease where the child has fever and irritability, particularly if there is a rash, erythema/desquamation of the extremities, conjunctivitis or cervical lymphadenopathy.

  • Hand, foot and mouth disease is another important acute cause of sore mouth in children.

  • Herpetic gingivostomatitis or oral candidiasis - as described under 'Causes of mouth ulcers', above.

  • Cancrum oris - this is a serious condition characterised by a rapid, painless and extensive necrosis of the oral cavity that can involve the cheek, nose, palate and bones.10 It almost always occurs in the context of poor oral hygiene and in lower-income countries. It may be preceded by excessive salivation, malodour from the mouth, grey discolouration and gingival ulcer formation.

Swellings in the mouth

NB: persistent swellings in the mouth should be referred for an oral surgery opinion to avoid missing oral cancers.

Swellings related to salivary glands:

  • Mucocele - a swelling of the inner surface of the mouth or ventral surface of the tongue.11 It is due to obstruction or rupture of a small salivary gland duct. It may have a bluish, translucent colour. When it occurs on the floor of the mouth it is known as a ranula.

  • Swellings of the sublingual salivary glands may be felt in the floor of the mouth.

Other swellings in the mouth may be due to a wide range of conditions. The list below outlines some of the more common causes:

Continue reading below

Red lesions of the oral mucosa

Red lesions of the oral mucosa are usually inflammatory in nature but may also be malignant, especially erythroplasia. The below lists some important causes of red lesions of the oral mucosa.

Common and important causes of red lesions in the mouth

Localised red patches

  • Candidiasis.

  • Lichen planus.

  • Erythroplasia/erythroplakia:

    • This is a premalignant or malignant lesion of the oral mucosa.

    • Although relatively rare, this is an important diagnosis not to miss. It tends to affect older patients above 60 years of age. Smoking is a risk factor.

    • The lesion looks red and velvety. It usually affects the mouth, the ventrum of the tongue, or the soft palate.

    • If suspected, refer to oral surgery for biopsy.12 These lesions have a high potential for malignancy.13

  • Angiomas, purpura or telangiectasias.

  • Burns and local trauma.

  • Kaposi's sarcoma.

Widespread redness
This may also be caused by many of the above, but also consider:

White lesions of the oral mucosa

Common and important causes of white lesions in the mouth

Infective causes

Mucocutaneous conditions


  • This term was formerly used to describe all white lesions of the oral mucosa, but is now given to those cases of unknown cause or those cases that are considered to be premalignant.15

  • Malignant transformation rates of oral leukoplakia range from 0.1-17.5%.15

  • Referral for biopsy is required to exclude or diagnose malignancy. However, most white lesions in the mouth are relatively benign keratoses caused by friction from teeth, cheek biting or tobacco smoking.

  • Various treatments have been used to try to encourage resolution of leukoplakic lesions and prevent malignant transformation, but their efficacy is unproven.16

  • These treatments include photodynamic therapy, cryotherapy and carbon dioxide laser ablation.

Hairy leukoplakia17

  • This is a white, asymptomatic lesion, usually on the lateral margin of the tongue.

  • It is associated with the Epstein-Barr virus and with immunocompromise.18

  • The lesions vary in appearance from smooth, flat, small lesions to irregular 'hairy' or 'feathery' lesions with prominent folds or projections, located on the margins, dorsal or ventral surfaces of the tongue or on buccal mucosa.

  • Treatment options include systemic antiviral therapy - eg, aciclovir 800 mg five times a day, topical therapy with podophyllin or retinoic acid, or cryotherapy.

For more details on both of these conditions see the separate Leukoplakia article.

Oral lichen planus19

This inflammatory condition commonly presents in older patients, with white patches affecting the mucosa of the mouth or tongue bilaterally. Involvement of the gums with oral lichen planus is known as 'desquamative gingivitis'.

  • Refer for biopsy and follow-up to exclude or monitor for malignancy.

  • There is up to 5% risk of malignant transformation, so long-term follow-up is required.20

  • Erosive, atrophic, ulcerative lesions require long-term treatment because of inflammation and severe pain.

  • Topical steroids, immunosuppressants, aloe vera, hyaluronic acid and antifungals have all been shown to be beneficial as treatment for this condition. They enhance healing, improve signs and symptoms of lesions and therefore improve the quality of patients' lives. Topical treatment is recommended mainly because of minimal side-effects.

  • Spontaneous remission can occur in up to 40%.21

See the separate Lichen Planus article.

Pigmented oral lesions

  • Blue/purple patches may be haemangiomas (will blanch with pressure), Kaposi's sarcoma (will not blanch) or purpura/ecchymoses (non-blanching, usually smaller lesions). Other rarer causes include heavy-metal toxicity or Peutz-Jeghers syndrome.

  • Brown or black lesions may be caused by staining from fillings (so-called amalgam tattoo) or naevi (freckles) but could, rarely, be due to a melanoma, so referral for biopsy should be considered.

  • If the tongue is furred and brown/black and/or appears hairy (particularly on its posterior portion), this is likely to be due to poor oral hygiene. It can be a problem in edentulous patients, those with a soft diet, those who smoke, and those who are fasting or ill or are using antimicrobials or chlorhexidine long-term. At its extreme this condition is termed black, hairy tongue. The condition is treated by improving oral hygiene, brushing the tongue or using a tongue scraper, increasing dietary fruit and roughage (pineapple is useful) and the use of sodium bicarbonate mouthwash.

  • Generalised pigmentation of the oral mucosa can be a normal feature in people of dark-skinned races. Certain medications (eg, phenothiazines, zidovudine, minocycline) and smoking can rarely cause it, as can Addison's disease or ectopic production of adrenocorticotrophic hormone (ACTH) - eg, by carcinoma of bronchus.

Dry mouth

Also known as xerostomia, this is characterised by a dry mouth sensation ± difficulty in speaking or swallowing, due to thick or sticky saliva. Individuals may also complain of halitosis. A wide range of conditions may cause this problem. Relatively common causes are listed below:

  • Psychogenic causes including BMS (see under 'Other causes of sore mouth', above).

  • Age-related.

  • Anticholinergic medication (particularly tricyclic antidepressants).

  • Various other medication, including diuretics.

  • Sjögren's syndrome.

  • Head and neck radiotherapy.

  • Any cause of salivary gland dysfunction (see the separate Salivary Gland Disorders article).

Treatment is with hydrating agents to provide moisture and comfort - usually gels or sprays. Good dental care is important because dry mouth predisposes individuals to tooth decay.


See the separate Halitosis article for further information.

Tooth and gum disorders

Tooth and periodontal problems are best dealt with by a dental general practitioner. However, current NHS dentistry provision is increasingly patchy, so such problems are presenting to medical primary care and emergency departments more frequently.

Further reading and references

  1. Plewa MC, Chatterjee K; Aphthous Stomatitis.
  2. Vashisht P, Goyal A, Hearth Holmes MP; Sweet Syndrome. StatPearls, Jan 2023.
  3. Herpes simplex - oral; NICE CKS, January 2023 (UK access only)
  4. Chi CC, Wang SH, Delamere FM, et al; Interventions for prevention of herpes simplex labialis (cold sores on the lips). Cochrane Database Syst Rev. 2015 Aug 7;(8):CD010095. doi: 10.1002/14651858.CD010095.pub2.
  5. Taylor M, Brizuela M, Raja A; Oral Candidiasis
  6. Bookout GP, Ladd M, Short RE; Burning Mouth Syndrome.
  7. Liu YF, Kim Y, Yoo T, et al; Burning mouth syndrome: a systematic review of treatments. Oral Dis. 2018 Apr;24(3):325-334. doi: 10.1111/odi.12660. Epub 2017 Mar 30.
  8. Jacob CN, John TM, R J; Geographic tongue. Cleve Clin J Med. 2016 Aug;83(8):565-6. doi: 10.3949/ccjm.83a.14011.
  9. Picciani BL, Domingos TA, Teixeira-Souza T, et al; Geographic tongue and psoriasis: clinical, histopathological, immunohistochemical and genetic correlation - a literature review. An Bras Dermatol. 2016 Jul-Aug;91(4):410-21. doi: 10.1590/abd1806-4841.20164288.
  10. Aaron SL, DeBlois KW; Acute Necrotizing Ulcerative Gingivitis.
  11. Huzaifa M, Soni A; Mucocele and Ranula.
  12. Suspected cancer: recognition and referral; NICE guideline (2015 - last updated October 2023)
  13. Scully C; Challenges in predicting which oral mucosal potentially malignant disease will progress to neoplasia. Oral Dis. 2014 Jan;20(1):1-5. doi: 10.1111/odi.12208.
  14. Dionne KR, Warnakulasuriya S, Zain RB, et al; Potentially malignant disorders of the oral cavity: current practice and future directions in the clinic and laboratory. Int J Cancer. 2014 Jan 31. doi: 10.1002/ijc.28754.
  15. Mohammed F, Fairozekhan AT; Leukoplakia, Oral
  16. Lodi G, Franchini R, Warnakulasuriya S, et al; Interventions for treating oral leukoplakia to prevent oral cancer. Cochrane Database Syst Rev. 2016 Jul 29;7:CD001829. doi: 10.1002/14651858.CD001829.pub4.
  17. Rathee M, Jain P; Hairy Leukoplakia
  18. Martins LL, Rosseto JHF, Andrade NS, et al; Diagnosis of Oral Hairy Leukoplakia: The Importance of EBV In Situ Hybridization. Int J Dent. 2017;2017:3457479. doi: 10.1155/2017/3457479. Epub 2017 Jul 17.
  19. Raj G, Raj M; Oral Lichen Planus.
  20. Muller S; Oral lichenoid lesions: distinguishing the benign from the deadly. Mod Pathol. 2017 Jan;30(s1):S54-S67. doi: 10.1038/modpathol.2016.121.
  21. Krupaa RJ, Sankari SL, Masthan KM, et al; Oral lichen planus: An overview. J Pharm Bioallied Sci. 2015 Apr;7(Suppl 1):S158-61. doi: 10.4103/0975-7406.155873.
  22. Kapoor U, Sharma G, Juneja M, et al; Halitosis: Current concepts on etiology, diagnosis and management. Eur J Dent. 2016 Apr-Jun;10(2):292-300. doi: 10.4103/1305-7456.178294.
  23. Halitosis; NICE CKS, September 2019 (UK access only)

Article history

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

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