Mouth ulcers that keep coming back: causes, red flags and when to get it checked

Recurrent aphthous stomatitis is the most common cause of repeated mouth ulcers and affects a sizeable minority of people at some point. It is not infectious. The precise cause is unclear, but immune and local factors play a role. For a few people, a nutritional deficiency or systemic disease drives it.

• Minor aphthous ulcers: small, shallow, on the inner cheeks, lips or tongue, healing without scarring in one to two weeks.

• Trauma from teeth, braces, dentures, brushing or hot food.

• Nutritional deficiencies: iron, vitamin B12 and folate, which are worth checking in anyone with frequent ulcers.

• Coeliac disease and inflammatory bowel disease (Crohn disease), which can present first with mouth ulcers.

• Medicines, including NSAIDs, nicorandil, methotrexate and some blood pressure tablets.

• Herpes simplex stomatitis and hand, foot and mouth disease, with clusters of small blisters and fever.

• Oral lichen planus, Behcet disease and pemphigus: ulcers with white lace-like patches, genital ulcers or blistering.

• Oral cancer, which can appear as a non-healing ulcer, red or white patch or lump, particularly in smokers and heavy drinkers.

Ulcers lasting longer than three weeks, ulcers that are large, hard or have raised edges, painless ulcers, a red or white patch, a lump in the mouth or neck, numbness, loosened teeth, difficulty swallowing, or ulcers with genital ulcers, eye inflammation, diarrhoea or weight loss need assessment.

• Urgent dentist or GP referral: any ulcer not healing within three weeks, or a persistent red or white patch.

• Same-day GP: ulcers with high fever, rash, difficulty swallowing or drinking, or eye pain.

• GP within weeks: ulcers more than three times a year, large or very painful ulcers, or with bowel symptoms.

• Pharmacist: a typical small ulcer for pain relief and gel.

They ask how often ulcers occur, how long they last, size, number and location, triggers, diet, bowel symptoms, genital or eye symptoms, medicines, smoking and alcohol. They examine the whole mouth, including the tongue, floor of the mouth and throat, and the neck glands.

• Full blood count, ferritin, B12 and folate: to look for deficiencies.

• Coeliac antibody test: when ulcers are frequent or there are digestive symptoms.

• Inflammatory markers and faecal calprotectin: if bowel disease is suspected.

• Biopsy of a persistent ulcer: the definitive test to exclude cancer or identify lichen planus or other diseases.

Rinse with warm salty water, use a soft toothbrush and avoid toothpaste containing sodium lauryl sulfate. Avoid spicy, acidic or abrasive foods during an episode. Over-the-counter gels, mouthwashes and corticosteroid lozenges ease pain and may speed healing. Correct any deficiency found.

A dentist or GP is the first contact on the NHS, with referral to oral medicine, ENT or gastroenterology as needed. Private dental and oral medicine consultations are available directly.