Common Causes
- Minor trauma (biting cheek, sharp food, braces)
- Stress
- Hormonal changes (some women notice ulcers around their period)
- Certain foods (acidic, spicy) can trigger in susceptible people
- Vitamin/mineral deficiencies — iron, B12, folate, zinc
- Coeliac disease
- Inflammatory bowel disease (Crohn's disease particularly)
- Behçet's disease (rare) — recurrent oral and genital ulcers
Investigation for Recurrent Ulcers
| Test | Checks For |
|---|---|
| FBC | Anaemia |
| Ferritin | Iron deficiency |
| Vitamin B12 + folate | Deficiency |
| Coeliac screen (tTG-IgA) | Coeliac disease — surprisingly common cause of recurrent ulcers |
| Zinc | Deficiency (less common) |
When to See a Doctor
- Ulcer persisting more than 3 weeks without healing — needs assessment to exclude oral cancer
- Unusually large or numerous ulcers
- Ulcers with fever or feeling generally unwell
- Recurrent ulcers alongside gut symptoms (diarrhoea, abdominal pain, weight loss)
- Ulcers with genital ulcers or eye inflammation (possible Behçet's disease)
Persistent Single Ulcer — Rule Out Oral CancerAny mouth ulcer persisting beyond 3 weeks, especially if painless, hard, or with irregular edges, should be assessed by a dentist or doctor to exclude oral cancer, particularly in smokers and heavy alcohol drinkers.
Simple Relief MeasuresAvoid acidic, spicy, or rough foods while healing. Salt water rinses, over-the-counter topical treatments (benzydamine mouthwash, hydrocortisone pellets), and avoiding toothpaste containing sodium lauryl sulphate (which triggers ulcers in some people) can help.
Are mouth ulcers contagious?
No — common aphthous ulcers are not contagious. However, cold sores (caused by herpes simplex virus) look different (fluid-filled blisters, usually on the lip border) and ARE contagious.
Can stress really cause mouth ulcers?
Yes — stress is a well-recognised trigger for aphthous ulcers in susceptible individuals, likely through effects on immune function.
Why do I get mouth ulcers with my period?
Hormonal fluctuations, particularly the drop in progesterone before menstruation, are linked to increased ulcer frequency in some women.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.