Oral Ulcers: Causes, Symptoms and Management

Dental Health · Oral and Dental Conditions

Oral Ulcers: Causes, Symptoms and Management

Oral ulcers are breaks in the lining of the mouth that may be painful, recurrent or slow to heal. Many short-lived ulcers follow minor trauma or are recurrent aphthous ulcers, but a persistent or unusual lesion can be a sign of infection, systemic disease, a medicine reaction or oral cancer. The pattern, site, duration, associated symptoms and patient history matter; a sore should not be labelled “just an ulcer” without assessment when it is persistent, atypical or accompanied by red flags.

This lesson helps dental and health-science learners describe oral ulcers, build a differential diagnosis, choose focused investigations, provide safe supportive care and recognise when to refer. It is educational content, not a diagnosis for an individual lesion. Assessment and treatment should be performed by appropriately trained professionals using current Ugandan guidance and referral pathways.

1. Definition and key terms

An ulcer is a break in the oral epithelium that extends into the underlying connective tissue. The surface may have a yellow-white fibrin coating and a red margin; this appearance can occur in several conditions and does not by itself establish the cause. Record what is seen before assigning a diagnosis.

• Acute ulcer: a short-duration lesion, often associated with a recent bite, burn, sharp tooth or acute infection.
• Recurrent ulceration: episodes that heal and return, sometimes at different sites. Ask how often they recur and whether each episode follows the same pattern.
• Aphthous stomatitis: a common, usually non-contagious condition characterised by recurrent round or oval ulcers on the non-keratinised lining mucosa. The cause is often uncertain.
• Induration: abnormal firmness on palpation. A firm base or rolled edge in a persistent ulcer is concerning and needs prompt professional assessment.
• Keratinised mucosa: tougher tissue such as attached gingiva and hard palate. Non-keratinised mucosa includes inner lips and cheeks, floor of mouth, ventral tongue and soft palate.
• Safety-netting: explaining what changes to watch for, when to return and how to access urgent review if the lesion does not heal or symptoms worsen.

2. Common causes and clinical patterns

Oral ulceration has a broad differential. A single, short-lived ulcer is often traumatic; multiple, recurrent or persistent lesions require a broader assessment. Patterns can guide the differential, but they overlap and should not replace clinical examination.

Recurrent aphthous stomatitis: three common patterns

Minor aphthae are the commonest pattern. They are usually shallow and small, occur on lining mucosa and heal without a scar. Major aphthae are larger and deeper, last longer and may scar. Herpetiform aphthae occur as crops of numerous tiny ulcers that may coalesce; despite the name, this pattern is not caused by herpes simplex. The terms describe clinical patterns, not severity alone. Ask about pain, recurrence, healing time and effect on nutrition or daily activity.

3. History taking for a patient with mouth ulcers

Start with an open question about the patient’s concern. A patient-centred history helps distinguish a self-limiting lesion from disease that needs targeted tests or referral.

• Onset and duration: When did the ulcer first appear? Has it healed at any time? Is it continuously present or does it recur? How long does each episode last?
• Site and number: Where is it? Is it in one place or are there lesions at several sites? Has the location changed between episodes?
• Evolution and symptoms: Ask about size, pain, burning, bleeding, discharge, numbness, odour, difficulty chewing, swallowing or speaking, and whether the lesion is enlarging or changing.
• Possible trauma: Ask about cheek or lip biting, a sharp tooth, recent dental work, dentures, braces, burns, vigorous brushing or hard foods.
• Associated symptoms: Fever, malaise, skin rash, blisters, genital sores, red or painful eyes, joint swelling, abdominal pain, diarrhoea, weight loss, swollen glands, fatigue or easy bruising can redirect the differential.
• Medical and dental history: Ask about prior episodes, known immune or inflammatory conditions, blood disorders, infections, recent illness, dental problems and previous investigations or treatment.
• Medicines and allergies: Record prescribed medicines, over-the-counter products, supplements, recent changes, chemotherapy or radiotherapy, immune-modifying treatment and previous drug reactions.
• Risk and exposure history: Ask respectfully about tobacco, alcohol, betel or areca nut use, diet, oral hygiene, relevant infectious exposures, sexual health where indicated, and barriers to obtaining care.
• Impact and goals: Determine whether pain limits fluids or food, affects sleep or communication, and what the patient is most concerned about.

4. Examination and documentation

Obtain consent, use standard infection-prevention precautions and provide adequate light. Examine the lips, labial and buccal mucosa, gingiva, alveolar mucosa, tongue, floor of mouth, palate and visible oropharynx in a consistent order. Check for trauma, dental causes, vesicles, plaques, multiple lesions, skin or lip involvement and regional lymph-node enlargement when clinically indicated and within the examiner’s competence.

Describe the lesion rather than writing only “mouth ulcer.” Record the exact site, number, approximate dimensions, shape, border, surface, colour, base, surrounding tissue, tenderness, firmness if palpated by a trained clinician, duration and relevant findings elsewhere in the mouth or body. Note whether it appears to be healing. A clinical photograph can help track change when the patient consents and images are stored securely under local policy.

5. Investigations: answer a clinical question

Typical minor aphthous or traumatic ulcers that heal as expected may not need laboratory tests. Investigations are selected when the pattern, persistence, severity or associated history raises a specific question. A suspicious persistent lesion should be referred for specialist assessment and possible biopsy; a swab or blood test should not delay that referral.

6. Management according to the likely cause

Treatment follows assessment. The aims are to reduce pain, support hydration and nutrition, remove an identifiable local cause and treat a confirmed underlying condition. Reassess lesions that are not following the expected course.

Supportive care for a short-lived, uncomplicated ulcer

• Explain that many minor traumatic and aphthous ulcers heal spontaneously; avoid promising a quick cure.
• Where safe, correct or arrange care for a sharp tooth, rough restoration, denture trauma or other continuing mechanical irritation.
• Use a soft toothbrush, maintain gentle oral hygiene and choose cool fluids and soft foods while the area is painful.
• Avoid foods, drinks or habits that the patient finds irritating, such as very hot, acidic, salty, spicy or rough foods. Encourage a balanced diet and adequate fluid intake.
• A pharmacist or qualified clinician may advise a suitable topical barrier, mouth rinse or pain-relieving product after checking age, pregnancy, allergies, medicines and the cause of the lesion.
• A topical corticosteroid may be considered by a clinician for a suitable aphthous pattern, particularly when started early. First assess for infection and other contraindications; steroid treatment should not be self-started for an undiagnosed persistent lesion.
• For frequent or severe recurrence, review potential triggers, medicine history, nutritional risk and systemic symptoms. Consider targeted investigation or specialist assessment.

Cause-directed and specialist care

Suspected viral infection, bacterial disease, immune-mediated disease, medicine-related ulceration or malignancy requires management directed by a qualified clinician. Antiviral, antimicrobial, anti-inflammatory or immunomodulatory treatment is not interchangeable and should not be chosen from appearance alone. Severe recurrent aphthous disease may require oral medicine or specialist review; systemic medicines can have significant adverse effects and need appropriate monitoring. Do not recommend that a patient stop prescribed treatment without consulting the responsible prescriber.

7. Red flags and referral

Emergency assessment is needed for breathing difficulty, inability to swallow saliva, rapidly increasing swelling, severe dehydration, altered consciousness or signs of serious systemic illness. Stabilise and refer through the local emergency pathway; do not wait for a routine dental appointment.

8. Common errors to avoid

• Assuming every round, pale ulcer is aphthous or that every lesion at the lip is a cold sore.
• Failing to record duration, exact site, edge, base, size or associated symptoms.
• Calling a lesion “traumatic” without addressing the suspected source and confirming that it heals.
• Repeatedly prescribing topical or systemic treatment without reviewing a persistent lesion.
• Applying caustic household substances, crushed tablets or aspirin directly to an ulcer, which can injure the mucosa.
• Prescribing antibiotics for uncomplicated aphthous ulcers or using steroids for a lesion before considering infection and other diagnoses.
• Delaying referral for an unexplained ulcer lasting more than three weeks, a suspicious lump or a red/white lesion.

9. Worked example: a persistent ulcer on the side of the tongue

10. Key takeaways

• Oral ulceration is a sign with many possible causes; duration, site, morphology, recurrence and associated symptoms guide assessment.
• Minor aphthous ulcers usually affect lining mucosa, are not contagious and heal without scarring; major aphthae last longer and may scar.
• Trauma is common, but the cause should be corrected where appropriate and healing confirmed.
• Take a focused medical, medicine, dental, nutritional and risk-factor history; inspect the entire oral cavity and document the lesion precisely.
• Use targeted investigations when the history or examination raises a clear question. Do not let tests or empirical treatment delay referral of a suspicious lesion.
• Supportive care can reduce irritation and pain while uncomplicated lesions heal. Cause-specific medicines require a diagnosis and professional judgement.
• An unexplained ulcer lasting more than three weeks, a suspicious lump, induration, a red/white patch or associated neck node needs prompt referral.
• Airway difficulty, inability to swallow, dehydration or severe systemic illness needs emergency assessment.

Self-assessment questions

1. What is an oral ulcer, and what features should be included in its description?
2. How do minor, major and herpetiform aphthae generally differ?
3. What history might suggest that oral ulcers are part of systemic disease?
4. Why is a traumatic explanation not enough when an ulcer remains after the suspected source is addressed?
5. When should an unexplained oral ulcer trigger prompt referral?
6. Name three associated features that need urgent or broader assessment.
7. Why should steroids or antibiotics not be started automatically for every mouth ulcer?

Suggested answers: (1) An ulcer is a break in the oral epithelium extending into connective tissue; record site, number, size, shape, edge, surface, colour, base, surrounding tissue, tenderness or induration, duration and change. (2) Minor aphthae are small and usually heal without scars; major aphthae are larger, deeper and last longer, sometimes scarring; herpetiform aphthae are many tiny grouped aphthae and are not herpes infection. (3) Genital ulcers, eye inflammation, skin lesions, joint symptoms, gastrointestinal symptoms, fever, weight loss or features of blood/nutritional illness. (4) Persistent ulceration needs reassessment because trauma may coexist with another disease and a suspicious lesion must not be missed. (5) When unexplained ulceration lasts longer than three weeks, or earlier if suspicious features are present; use the local referral pathway. (6) Breathing or swallowing difficulty, dehydration, fever with serious illness, eye or genital lesions, induration, neck node or unexplained weight loss are examples. (7) These treatments address different causes, can cause harm or mask signs, and require an appropriate clinical assessment.

Further reading and learning resources

• Supplementary slides: Oral ulcers
• NHS: Mouth ulcers, common causes, self-care and when to seek review
• University College London Hospitals: Recurrent aphthous stomatitis
• NICE guideline NG12: oral ulceration and head-and-neck referral recommendations, updated April 2026
• American Dental Association: Oral cancer guideline
• Uganda Ministry of Health: MediGuide clinical guidelines platform

Continue learning: Dental history taking and oral examination · Dental anaesthesia: local and general methods · Tooth extraction: indications, techniques and complications · Oral health education.

Educational content for students and health workers. It does not replace patient-specific examination, supervised clinical training, current Ugandan guidance or referral protocols. Consult or refer to a suitably qualified clinician for persistent or suspicious lesions.