Mouth Ulcers: Common, Painful, and Occasionally Serious

Recurrent aphthous ulcers — the small round sores with a white or yellow centre and a red rim — affect perhaps one in five people. They are not infectious, not contagious, and not caused by any single thing. But there is one rule worth knowing before the rest.

The three-week rule

Any ulcer that has not healed within three weeks needs to be examined. Not watched for another month. Ordinary ulcers heal in seven to fourteen days. One that persists, particularly if it is painless, has raised or rolled edges, is hard to the touch, bleeds easily, or sits on the side of the tongue or floor of the mouth, must be looked at to exclude oral cancer. India has among the highest rates of oral cancer in the world, largely driven by tobacco and areca nut (gutkha, paan masala), and it is highly treatable when caught early.

Why ordinary ulcers appear

• Minor trauma — biting your cheek, a sharp tooth or filling, a toothbrush jab, orthodontic brackets.
• Stress and lack of sleep, which is why they arrive during exams and deadlines.
• Nutritional deficiency — iron, vitamin B12, folate. Worth testing if ulcers are frequent.
• Hormonal cycles.
• Sodium lauryl sulphate (SLS) in toothpaste, which triggers ulcers in some people. Switching to an SLS-free paste helps a subset dramatically.
• Certain foods — citrus, tomato, chocolate, nuts, spicy food.
• Underlying conditions — coeliac disease, inflammatory bowel disease, Behçet's, and some medications.

What helps

Nothing makes an ulcer vanish, but several things reduce pain and speed healing: a salt-water or bicarbonate rinse; topical anaesthetic or protective gels from a pharmacy; chlorhexidine mouthwash to prevent secondary infection; avoiding acidic, salty and spicy food while it heals; and a soft toothbrush. If they are frequent, a blood test for iron, B12 and folate is worthwhile — correcting a deficiency can stop the cycle entirely.

What it might not be

Not every sore is an aphthous ulcer. Cold sores (herpes simplex) usually appear on the lip border as a cluster of blisters and are contagious. Oral thrush shows as white patches that rub off leaving redness, and points to antibiotics, inhaled steroids, dry mouth or uncontrolled diabetes. Lichen planus produces lacy white lines, often on the cheeks, and needs monitoring. A traumatic ulcer from a sharp tooth heals as soon as the sharp edge is smoothed — which takes minutes.

When to book

See a dentist for any ulcer lasting more than three weeks; ulcers that keep returning in the same place; unusually large ulcers; ulcers with fever or feeling unwell; any white or red patch that does not rub off; a lump, numbness, or difficulty swallowing. If you use tobacco or areca nut in any form, have your mouth screened at every check-up regardless of symptoms.

Frequently asked questions

Are mouth ulcers contagious?

Aphthous ulcers are not. Cold sores caused by herpes simplex are contagious, but they usually appear on the lip border rather than inside the mouth.

Why do I keep getting ulcers in the same spot?

Usually repeated trauma from the same source — a sharp tooth edge, a rough filling, or a denture rubbing. Smoothing the cause fixes it. Recurrence in exactly the same place should always be examined.

Can toothpaste cause mouth ulcers?

Sodium lauryl sulphate, the foaming agent in most toothpastes, triggers ulcers in some people. If you get them frequently, trying an SLS-free toothpaste for a couple of months is a cheap experiment.

When is a mouth ulcer a sign of cancer?

Concerning features are: lasting over three weeks, painless, firm or hard, raised rolled edges, bleeding easily, or located on the side of the tongue or floor of the mouth. Any of these need prompt assessment.

Talk to a dentist in Dehradun