In shortStomatitis means inflammation of the mouth lining, most commonly appearing as painful ulcers. Ordinary aphthous ulcers are round, shallow, with a white-yellow base and a red rim, and heal within about two weeks without scarring. The important rule is duration: any ulcer that has not healed in three weeks should be examined rather than treated at home.
Distinguishing the common types
| Type | Appearance | Course |
|---|
| Minor aphthous ulcer | Under 1 cm, white-yellow base, red rim | Heals in 7–14 days, no scar |
| Major aphthous ulcer | Over 1 cm, deeper | Weeks, may scar |
| Herpetiform | Clusters of tiny ulcers | Merge, heal in 1–2 weeks |
| Traumatic ulcer | Irregular, beside a sharp edge or appliance | Heals once the cause is removed |
| Herpetic (cold sore type) | Vesicles first, often on the lip border | Crusts and heals in 7–10 days |
| Candidal | White plaques that can be wiped off | Needs antifungal treatment |
What triggers recurrent aphthous ulcers
- Local trauma — a toothbrush slip, a sharp crisp, a cheek bite, an orthodontic bracket, or the edge of a broken tooth.
- Stress and disturbed sleep, which is why they cluster around exam periods, deployments, and relocations.
- Hormonal fluctuation in some patients.
- Sodium lauryl sulphate in toothpaste — a genuine trigger in a subset of frequent sufferers, and worth a trial of an SLS-free paste.
- Nutritional deficiency — iron, folate, vitamin B12, and zinc. Frequent recurrent ulcers justify blood tests rather than repeated topical gels.
- Acidic and spicy foods, which more often aggravate an existing ulcer than initiate one.
- Certain medications, including some anti-inflammatories and beta blockers.
The one thing recurrent ulcers are usually not is a hygiene failure. Patients frequently assume they have done something wrong, and brush harder as a result, which adds trauma to inflammation. Aphthous ulceration is an immune-mediated process with identifiable triggers, and the productive approach is finding the trigger — deficiency, toothpaste ingredient, a sharp tooth edge, or a stressful period — rather than escalating the scrubbing.
Managing an episode
- Remove the mechanical cause if there is one — smooth a sharp edge, adjust an appliance, replace a worn brush.
- Topical protection or anaesthetic gel to allow eating and drinking.
- Avoid acidic, salty, spicy, and very hot foods while it heals; these prolong the discomfort without changing the healing time.
- Saltwater rinsing and gentle continued cleaning of the area — stopping brushing near an ulcer makes matters worse.
- Maintain hydration and nutrition, which is a genuine concern with widespread ulceration, particularly in children.
- Prescribed topical corticosteroid where episodes are frequent or severe, under supervision.
When it is more than a canker sore
Have it examined if any of the following apply: an ulcer that has not healed within three weeks; an ulcer with a hard, rolled, or indurated edge; ulceration accompanied by fever, rash, or genital or eye lesions; ulcers appearing alongside unexplained weight loss or persistent fatigue; a lump or
white patch that develops at the site; or a sudden change in the pattern of long-standing ulcers. Duration is the most useful single criterion available to you at home, because a persistent non-healing ulcer requires assessment to exclude
more serious causes. This is general information and not a diagnosis.
Recurrent ulcers as a systemic clue
Frequently recurring oral ulceration is sometimes the earliest visible sign of something broader — iron or B12 deficiency, coeliac disease, inflammatory bowel disease, or Behçet syndrome when combined with genital ulcers and eye inflammation. This does not mean every canker sore warrants investigation, but a pattern of several episodes a year, or ulcers that are unusually large or slow to heal, is a reasonable prompt for blood tests and a broader history rather than another tube of gel.
Notes for patients based in Korea
Ulcer episodes cluster reliably around relocation, deployment cycles, and examination periods, so a run of them during a difficult few months is not surprising. What matters is applying the three-week rule regardless of circumstances: a persistent ulcer needs looking at even when there is an obvious stress explanation available. We are around 30 minutes from Camp Humphreys and consultations are conducted in English. Book an appointment if an ulcer is not settling.
Frequently asked questions
How long should a mouth ulcer take to heal?
An ordinary minor aphthous ulcer heals within about seven to fourteen days and leaves no scar. Larger ulcers can take several weeks. The practical rule worth remembering is three weeks: any ulcer still present after that should be examined rather than managed at home, because persistence is the most useful warning sign available without a clinical examination.
What causes recurrent canker sores?
Common triggers include local trauma, stress and poor sleep, hormonal fluctuation, sodium lauryl sulphate in toothpaste, and deficiencies of iron, folate, B12, or zinc. It is an immune-mediated process rather than a hygiene failure, so brushing harder does not help and adds trauma. Frequent recurrences justify blood tests and a trigger review rather than repeated topical gels alone.
Can toothpaste cause mouth ulcers?
In a subset of people, yes. Sodium lauryl sulphate, the foaming agent in most toothpastes, is a recognised trigger for recurrent aphthous ulceration in susceptible individuals. Switching to an SLS-free paste for a couple of months is a simple, low-cost test. If episodes reduce noticeably, you have identified a trigger you control entirely.
Are mouth ulcers contagious?
Ordinary aphthous ulcers are not; they are an immune-mediated reaction, not an infection. Herpetic lesions are different and are contagious, particularly while blistering, and typically start as small vesicles often at the lip border rather than as a single round ulcer inside the cheek. If you are unsure which you have, that distinction is worth confirming.
Should I stop brushing near an ulcer?
No, though gently is the operative word. Abandoning cleaning around the area allows plaque to accumulate and inflammation to worsen, which slows healing. Use a soft brush, be careful, and keep cleaning. If a sharp tooth edge or an appliance caused the ulcer in the first place, having that smoothed is more useful than avoiding the area.
When is a mouth ulcer serious?
When it has not healed in three weeks, has a hard or rolled edge, is accompanied by a lump or a white patch, or comes with fever, rash, eye or genital lesions, unexplained weight loss, or persistent fatigue. A sudden change in the pattern of long-standing ulcers also warrants assessment. These features do not mean something serious is present, only that examination is needed rather than home care.