Mouth ulcers: causes and when to get checked in Luxembourg

A mouth ulcer — also called a canker sore or aphthous ulcer — is a small, round or oval sore on the lining of the mouth, with a whitish or yellowish centre and a red rim. It is not contagious and heals on its own within about ten days, yet the pain it causes is out of all proportion to its size. In Luxembourg, the right professionals to see are a dentist or a general practitioner (GP), and one rule matters above all: any mouth sore that has not healed after two to three weeks must absolutely be examined.

Tiny sore, outsized pain

A few millimetres are enough to ruin a meal. An ulcer on the edge of the tongue or inside the lip turns a bite of bread, a sip of orange juice or an ordinary tooth-brushing session into an ordeal. The pain is a sharp burning, reawakened by every contact, and some people change the way they eat or even speak for a few days.

That early, intense soreness is actually a distinguishing feature. A canker sore hurts from the very start and then gradually settles as it heals. A cold sore (herpes), by contrast, usually sits on the outer edge of the lips, starts as a cluster of small blisters and is contagious — the two are often mixed up, but they are different conditions.

What sets them off

There is no single known cause, but most people who get recurrent ulcers learn to recognise their personal triggers. Three groups come up again and again:

• Certain foods: nuts, hard cheeses, tomatoes, citrus fruit, pineapple, chocolate, spicy dishes. The list is individual — a food that is harmless for one person reliably sets off ulcers in another.
• Stress and fatigue: exam periods, heavy workloads, short nights. Flare-ups tend to arrive exactly when your reserves are lowest.
• Minor injuries inside the mouth: biting your cheek, brushing too hard, braces or a denture that rubs, a chipped tooth that keeps scratching the same spot.

Hormonal changes, stopping smoking and certain deficiencies (iron, B-group vitamins) can also play a part. When ulcers keep coming back in repeated episodes, doctors speak of recurrent aphthous stomatitis — worth a medical review once it becomes frequent or genuinely disabling.

Healing on its own in about ten days

The usual course is reassuring: a tingling or slightly sore spot for a day or two, then the ulcer appears, the pain peaks over the first few days, and everything heals completely within one to two weeks, leaving no scar. A single, ordinary ulcer needs no treatment at all.

While you wait it out, you can make life easier: avoid acidic, spicy or sharp-edged foods during the flare-up, favour lukewarm or cool dishes, and brush gently with a soft toothbrush. Pharmacies stock soothing or protective gels and mouth rinses that can take the edge off the pain; your pharmacist, dentist or doctor can point you to what suits your situation.

The ulcer that will not heal: the line you must not cross

This is the key message of this page. An ordinary mouth ulcer heals by itself in ten days, two weeks at most. A sore in the mouth that persists beyond two to three weeks is no longer an ordinary ulcer and must absolutely be shown to a dentist or a GP — even if it does not hurt, and especially if it does not hurt. Some more serious lesions of the oral lining can look deceptively like a canker sore that is simply slow to heal, and only a professional examination, sometimes with a small tissue sample, can tell the difference.

You should also seek advice without waiting out the two weeks if the ulcers are unusually numerous or large, if they come with fever, marked tiredness or sores on other parts of the body, or if they make eating and drinking genuinely impossible — in a child who stops drinking, act quickly, and in a real emergency call 112. Very frequent flare-ups also justify a check-up: your doctor may look for a deficiency or an underlying condition of which repeated mouth ulcers are sometimes the visible sign.

How it works in Luxembourg

No referral is needed: in Luxembourg you can book directly with a dentist or a GP. The dentist is the natural choice when the sore seems linked to a tooth, a denture or braces rubbing against the mouth lining; the GP is right for repeated flare-ups, ulcers accompanied by other symptoms, or a full check-up for recurrent ulcers. Consultations are reimbursed by the National Health Fund (CNS) under the usual conditions. You can find a dentist or a GP near you and book an appointment directly on Doctipro.

Keeping flare-ups at bay

You cannot prevent every ulcer, but you can space them out: identify your trigger foods and go easy on them, keep up gentle but regular oral hygiene, ask your dentist to check any denture, brace or tooth that keeps injuring the same spot, and protect your sleep during stressful periods. Keeping a short note of the circumstances around each flare-up often reveals the culprit — and gives your doctor useful clues at the consultation.