Mouth Ulcers
Painful breaks in the lining of the mouth, usually harmless and self-limiting.
Last revised
Key takeaways
- Usual healing time: within 2 weeks
- Threshold for urgent assessment: more than 3 weeks
- Most useful single change: Use an antimicrobial mouthwash or a topical analgesic gel for comfort.
- Commonest mistake: Ignoring an ulcer lasting more than three weeks.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Nearly all settle in under two weeks, and the ones that do not are the reason the three-week rule exists.
The numbers, in one place
| Measure | Figure |
|---|---|
| Usual healing time | within 2 weeks |
| Threshold for urgent assessment | more than 3 weeks |
| Common triggers | trauma, stress, hormonal change, some toothpastes |
| Associated conditions | coeliac disease, iron, B12 or folate deficiency, IBD |
What helps
- Use an antimicrobial mouthwash or a topical analgesic gel for comfort
- Avoid spicy, acidic and salty foods while healing
- Try a toothpaste without sodium lauryl sulfate if ulcers are recurrent
- Ask for blood tests if ulcers keep recurring
What to avoid
- Ignoring an ulcer lasting more than three weeks
- Assuming recurrent ulcers are just stress without investigation
- Using topical steroids long term without dental advice
Where to go next
- A Q and A on Mouth Ulcers
- The Short Guide to Mouth Ulcers
- What the Guidance Really Says About Bad Breath
- Sensitive Teeth: What the Evidence Actually Says
When to get help
See a dentist or GP urgently for any mouth ulcer, lump, or red or white patch lasting more than three weeks — this is the standard threshold for mouth cancer referral. Also seek assessment for ulcers with weight loss, diarrhoea, fatigue, or ulcers elsewhere on the body.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.