When should you worry about a mouth ulcer?

The two-week rule

An ordinary aphthous ulcer heals within one to two weeks, without scarring. That is the benchmark, and it is what makes the answer simple: anything still present beyond two weeks should be examined.

Not treated at home for another fortnight. Examined.

The other reasons to get one looked at

• It keeps recurring.
• It is unusually large or severe.
• It comes with fever or difficulty swallowing.

Why a non-healing ulcer is the one that matters

Most mouth ulcers have an ordinary cause and resolve on their own. An ulcer that does not follow that course is behaving differently, and the reason needs identifying rather than assuming. That is a job for someone looking at it, not for a page.

This is not a reason to panic about a sore spot you got three days ago from biting your cheek. It is a reason to put a date in your head when one appears, and to act if it passes.

Recurrent ulcers point somewhere

Frequent ulcers can relate to nutritional deficiency or an underlying medical condition, alongside the ordinary triggers of minor injury, stress, hormonal changes, certain foods and some toothpaste ingredients. If you get them constantly, that pattern is itself worth investigating.

If they keep appearing in the same place, the cause is usually physical — something rubbing. That is covered separately and is often quickly fixed.

Ulcers and cold sores are not the same thing

Common aphthous ulcers are not contagious. Cold sores appear on the lip rather than inside the mouth, are caused by a virus, and are a different thing — worth distinguishing at an examination rather than by guessing.

Meanwhile

Topical gels or rinses with a numbing or protective agent help, as does avoiding spicy, acidic, salty and very hot food while it heals. A soft brush and gentle cleaning around the area reduce irritation. A warm saltwater rinse can soothe and keep it clean — a comfort measure rather than a cure, and not a substitute for getting a persistent one looked at.

Full detail on the mouth ulcers page; see also why ulcers keep coming back. Consultation ₹500, waived against treatment.