Mouth Ulcers
Also known as Aphthous ulcers, Canker sores
This article is general health information for the selected condition. It is not a diagnosis and does not replace clinical judgement. If you have questions or need treatment advice, please consult a qualified healthcare professional.
What is mouth ulcers?
Mouth ulcers are painful round sores on the inside of the cheeks, lips or tongue. Most are harmless and heal within one to two weeks without treatment. The important exception is an ulcer lasting more than three weeks, which needs assessment because it can be a sign of mouth cancer.
Causes
- Minor trauma from biting, braces or a toothbrush
- Stress and tiredness
- Hormonal changes
- Iron, vitamin B12 or folate deficiency
- Coeliac or inflammatory bowel disease
- Certain medicines including anti inflammatories
- Sodium lauryl sulfate in some toothpastes
Symptoms
- Round or oval sores with a white, yellow or grey centre
- A red inflamed border
- Pain made worse by eating, drinking or brushing
- One or several at a time
- Usually inside the cheeks, lips or under the tongue
- Healing within one to two weeks
Risk factors
- Family history of recurrent ulcers
- Stress and poor sleep
- Nutritional deficiency
- Autoimmune and inflammatory bowel conditions
- Stopping smoking, which can trigger a temporary increase
- Weakened immune system
Diagnosis
- Clinical examination of the mouth
- Blood tests for iron, B12, folate and coeliac disease if recurrent
- Biopsy for any ulcer lasting more than three weeks
- Assessment for underlying inflammatory disease
Treatment
- Antimicrobial or anaesthetic mouthwash
- Topical corticosteroid preparations
- Protective pastes to cover the ulcer
- Correcting nutritional deficiency
- Treating an underlying condition
- Urgent referral for ulcers persisting beyond three weeks
Self care
- Use a soft toothbrush and a toothpaste without sodium lauryl sulfate
- Avoid acidic, spicy, salty and very hot foods while healing
- Rinse with warm salt water
- Drink through a straw if drinks sting
- Use over the counter gels for pain before meals
- Reduce stress and improve sleep where possible
When to see a doctor
Book an appointment if:
- An ulcer lasting more than three weeks
- Ulcers that keep recurring
- Ulcers with diarrhoea, weight loss or fatigue
- Unusually large or very painful ulcers
- Ulcers with a rash or genital ulcers
- A lump or red or white patch in the mouth
Some symptoms need emergency care rather than an appointment. See the warning signs listed above.
Prevention
- Treat nutritional deficiencies
- Use a soft toothbrush and avoid trauma
- Try a toothpaste free of sodium lauryl sulfate
- Manage stress and sleep
- Attend regular dental checks
- Stop smoking, which reduces mouth cancer risk substantially
Outlook
Ordinary mouth ulcers heal within one to two weeks and leave no scar. Recurrent ulcers can continue for years, though frequency usually reduces with age and improves when any deficiency or underlying condition is treated. The key safety point is that any ulcer persisting beyond three weeks needs assessment.
Common questions
When is a mouth ulcer serious?
Any ulcer, lump or red or white patch lasting more than three weeks should be examined, since this is the main warning sign for mouth cancer. Painless ulcers are not more reassuring, they are often less so.
Why do I keep getting them?
Recurrent ulcers often run in families, but iron, B12 or folate deficiency, coeliac disease and inflammatory bowel disease are all treatable causes worth checking with a blood test.
References
Important: Dard AI is not a medical device and does not diagnose, treat, or replace clinician judgement. This article is general information only. Always consult a qualified healthcare professional about diagnosis and treatment, and seek emergency care for severe or rapidly worsening symptoms.