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Wellbeing2 min read · July 22, 2026

by Dr.ssa Irene Ferrara

Canker sores and stomatitis: a quick guide

Small, very painful and almost always harmless: what aphthous ulcers are, what triggers them and when a visit is needed instead.

Canker sores are small round ulcers, white with a red border, that burn out of all proportion to their size. Almost always harmless — with a few rules worth knowing.

What triggers them

  • Small traumas: accidental bites, toothbrush, braces
  • Stress and fatigue
  • Deficiencies (iron, B12, folate) in recurrent forms
  • Certain foods (citrus, tomato, nuts) in predisposed people

Getting through them

  1. Over-the-counter barrier gels to protect the ulcer.
  2. Avoid acidic, spicy and crunchy foods for a few days.
  3. Gentle hygiene: a clean mouth heals faster.
  4. For recurrent forms: an assessment at the practice and possibly tests with your doctor.

The signal not to ignore

An ulcer that doesn't heal within two weeks is not an aphtha until proven otherwise: it must be seen. It is a fundamental prudence rule in oral mucosa care, in line with WHO's focus on early detection of oral lesions.

Sources

Frequently asked questions

Are canker sores contagious?

No: unlike cold sores, aphthae are not infectious. They are inflammatory ulcers linked to predisposition, stress, small traumas or deficiencies.

How long do they last?

Usually 7-14 days, with peak discomfort in the first days. Barrier gels and dietary care help you through.

When should I worry?

If an ulcer doesn't heal within two weeks, is very large, recurs very often or comes with fever: then a visit is needed — no alarmism, no delays.

Clinical review: Dr.ssa Irene Ferrara

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