Mouth Ulcers

Mouth ulcers are small painful sores on the lining of the mouth, tongue or lips. The ordinary kind — aphthous ulcers — affect around one in five people, appear for no obvious reason, and heal within one to two weeks without leaving a mark.

A single ulcer after biting your cheek needs nothing at all.

Recurrent ulcers are a different question, and one that is under-investigated. They are a recognised sign of iron, B12 and folate deficiency, and of coeliac disease — all of which are eminently treatable, and none of which will be found unless someone thinks to look.

Simple causes

• Minor trauma — biting your cheek, a sharp tooth, braces, an ill-fitting denture
• Stress and poor sleep, which genuinely do trigger recurrences
• Sodium lauryl sulphate in toothpaste — switching to an SLS-free toothpaste helps a meaningful proportion of people with recurrent ulcers, and costs almost nothing to try
• Certain foods — chocolate, coffee, tomatoes, citrus, nuts
• Hormonal changes around the menstrual cycle
• Stopping smoking, which paradoxically triggers ulcers in some people

Deficiencies — the group worth testing for

• Iron deficiency
• B12 deficiency
• Folate deficiency
• Zinc deficiency

Deficiencies are found in a significant minority of people with recurrent ulcers, and correcting them frequently stops the ulcers entirely.

Underlying conditions

• Coeliac disease — recurrent ulcers are a recognised presentation, sometimes the only one
• Inflammatory bowel disease — Crohn's in particular
• Behçet's disease — mouth and genital ulcers together
• Oral lichen planus
• Immune deficiency, including HIV
• Medication — NSAIDs, nicorandil, methotrexate and beta blockers among others

Infections

• Herpes simplex, particularly a first infection in a child or young adult
• Hand, foot and mouth disease
• Oral thrush, which is a different appearance but often confused

The important question is not what a single ulcer is, but whether the pattern warrants investigation.

We ask about: how often they occur and how long each lasts; how many at a time and their size; whether there are ulcers or symptoms elsewhere — genital ulcers, eye inflammation, bowel symptoms, joint pain; your diet and any restriction; your medications; and any family history of coeliac or inflammatory bowel disease.

For recurrent ulcers we routinely arrange: full blood count, ferritin, B12 and folate, and coeliac screening. That panel is inexpensive and finds a treatable cause often enough to be worth doing as standard.

A note on coeliac testing: you must still be eating gluten for the test to be valid — more than one gluten-containing meal a day for at least six weeks. Cutting it out first makes the test unreliable.

For treatment we can advise on and prescribe topical steroids, anaesthetic gels, chlorhexidine and, for severe recurrent disease, systemic options — and we can refer to oral medicine where the picture warrants it.

For anything suspicious, or any ulcer past three weeks, we arrange urgent referral. This is one where remote assessment recognises the problem and routes it, rather than managing it.

When should I worry about a mouth ulcer?

Three weeks. A normal ulcer is very painful, small, and heals within one to two weeks. Anything that persists beyond three weeks should be examined — particularly if it is painless, has firm or rolled edges, sits on the side of the tongue or the floor of the mouth, or comes with a neck lump.

Most such ulcers turn out to be caused by trauma from a sharp tooth. The examination happens anyway, because mouth cancer found early is very treatable and found late is not.

Should I see a dentist or a GP?

A dentist — and this genuinely is the better route. Dentists examine mouths daily, have proper lighting and mirrors, and can refer straight onto the urgent two-week head and neck pathway. Most practices will see someone with a non-healing ulcer without them being a registered patient, and it is usually faster than any other option.

Isn't a painless ulcer less serious?

No — it is the other way round, and this is the most important misconception here. Ordinary aphthous ulcers are notoriously painful for their size. A painless, persistent ulcer has lost that expected inflammatory response, which is precisely why painlessness is treated as a warning feature rather than a reassuring one.

Could my toothpaste be causing them?

Quite possibly. Sodium lauryl sulfate, the detergent that makes toothpaste foam, is associated with recurrent aphthous ulcers in susceptible people, and switching to an SLS-free toothpaste reduces both frequency and severity for many of them.

It costs nothing to try, takes a month or so to show, and is one of the more reliably useful pieces of advice for anyone getting ulcers repeatedly.

Is it a vitamin deficiency?

Often, and it is worth testing rather than supplementing blindly. Low iron, B12 and folate are all well-recognised causes of recurrent mouth ulcers, and correcting them frequently stops the ulcers entirely.

Coeliac disease deserves a specific mention — recurrent mouth ulcers can be its earliest sign, sometimes years before any bowel symptoms. Screening for it is a simple blood test, and it must be done while you are still eating gluten.

Are mouth ulcers contagious?

Ordinary aphthous ulcers are not contagious at all. Cold sores are, and the two get confused. The distinction is location: cold sores appear on the lip border and around the mouth, start as blisters, and tingle beforehand. Aphthous ulcers appear inside the mouth — on the inner cheeks, tongue and lips — and are never blisters.

I take nicorandil for angina. Is that relevant?

Very. Nicorandil causes severe, persistent, painful ulceration — in the mouth, and sometimes around the anus and elsewhere. The ulcers are typically large, deep and unresponsive to every standard treatment, and they resolve only when the drug is stopped.

It is a well-documented effect that is still regularly missed, sometimes for years. Raise it with whoever manages your heart medication — do not stop it yourself, as there are alternatives that need arranging properly.

What actually helps them heal faster?

Honestly, not much accelerates healing — most treatment is about comfort while the ulcer runs its course. What works for pain: benzydamine mouthwash or spray, topical anaesthetic gel before meals, warm salt water rinses, and a chlorhexidine mouthwash to prevent secondary infection.

For severe or frequently recurring ulcers, topical steroid preparations are effective and can be prescribed. Where ulcers are relentless, treating the underlying deficiency or condition is what actually breaks the cycle.