Mouth sores

Most straightforward ulcers heal within about two weeks. The widely used clinical threshold is three weeks: anything that has not resolved by then should be examined instead of watched further. This applies regardless of how it looks or how much it hurts. A painless persistent ulcer is if anything more concerning than a painful one, because pain often reflects a simple traumatic or aphthous cause while painless persistence does not.

Recurrent aphthous ulceration often has no single identifiable cause, but several contributors are worth excluding when ulcers are frequent: iron, folate or vitamin B12 deficiency, coeliac disease, inflammatory bowel disease, medication effects, and sodium lauryl sulphate in toothpaste, which aggravates ulcers in some people. Stress and hormonal cycles are commonly reported triggers. A pattern of frequent ulcers justifies investigation instead of repeatedly treating each episode symptomatically.

It needs examining, not assuming either way. A white patch that wipes away is often fungal and treatable. One that cannot be wiped away, has no obvious cause such as a rubbing denture, and persists is the type that warrants assessment and often biopsy, because appearance is unreliable at distinguishing harmless keratosis from something requiring treatment. Most turn out to be benign, but that is established by looking properly instead of by waiting.

The great majority of mouth sores are benign, so worry is usually unwarranted, but the three-week rule exists precisely because the conditions that matter are far more treatable when found early, and because they cannot be distinguished by appearance. If you use tobacco in any form, drink heavily, or use betel or areca nut, the threshold for getting a persistent lesion examined should be lower. Being examined is straightforward; late diagnosis is not.

Sodium lauryl sulphate, the foaming agent in many toothpastes, aggravates ulceration in some people, and switching to a formulation without it is a reasonable and cheap experiment if you get recurrent ulcers. It is not a cause in everyone and it will not resolve ulcers with another underlying driver. If ulcers persist after several weeks on an SLS-free paste, that points toward investigating other causes instead of continuing to change products.

Have the denture adjusted, not tolerating it or leaving it out indefinitely. A traumatic ulcer from a denture edge should heal within days once the cause is removed, and that response is itself diagnostically useful. What matters is that removing the cause is time-limited and reviewed: if the ulcer has not healed within about two to three weeks after the denture has been adjusted, it needs examining instead of adjusting again.

Stress is a commonly reported trigger for recurrent aphthous ulceration, though the exact mechanism is not fully understood and stress alone does not explain every case. Nutritional deficiency, medication effects and other contributors are still worth excluding when ulcers are frequent. Noticing a pattern between stressful periods and ulcer flares is useful information to share, but it does not substitute for investigation if ulcers are severe or very frequent.

No: they are different conditions with different causes. Cold sores are caused by the herpes simplex virus, typically appear on the outer lip or skin around the mouth instead of inside it, and are contagious. Canker sores (aphthous ulcers) occur inside the mouth on the soft tissue, are not caused by a virus, and are not contagious. The two are commonly confused because both are painful mouth sores, but their treatment and management differ.

Some people report a clear pattern of recurrent aphthous ulcers linked to their menstrual cycle, which is a recognized though not fully explained association. If you notice a consistent hormonal pattern to your ulcers, mentioning it is useful diagnostic information, though it does not rule out other contributors and persistent or unusually frequent ulceration should still be assessed on its own merits.

A small traumatic ulcer can occasionally develop where a cheek or lip was accidentally bitten while still numb from local anesthetic, or from minor irritation during a procedure, and this typically heals within days like any other traumatic ulcer once the minor injury resolves. It is not typically a sign of anything wrong with the treatment itself, but a sore that persists well beyond the usual healing window should still be assessed, not assumed to be routine.

Some people report that specific foods, commonly acidic fruits, spicy foods, or foods containing certain preservatives, seem to trigger or worsen their recurrent ulcers, though this varies considerably between individuals and is not a universal pattern. Keeping a simple record of ulcer timing alongside diet can help identify a personal trigger, but this observational approach does not replace investigation where ulcers are frequent, severe or otherwise concerning.

No: avoiding cleaning entirely around a sore area risks a build-up of plaque that can delay healing or introduce infection, so a gentler approach with a soft brush around the ulcer, instead of skipping that area altogether, is generally the better balance between comfort and keeping the site clean while it heals.