Mouth Ulcers

Painful sores inside the mouth. Most are harmless and heal within two weeks.

MouthLast updated: 21 October 2026

Quick Summary

Primary Symptoms

Round or oval sores with a white or yellow centre and red edge, pain when eating or drinking.

Common Treatments

Pain-relieving gels, mouthwashes, avoiding spicy or sharp foods; see a doctor if they don't heal.

Risk Factors

Minor injury, stress, vitamin deficiencies (B12, iron, folate), hormonal changes and some conditions.

OverviewSymptomsCausesTreatmentFAQ

Overview

Most mouth ulcers (aphthous ulcers) aren't contagious and heal on their own.

An ulcer lasting more than three weeks, especially in tobacco users, must be checked to rule out mouth cancer.

Symptoms

Painful sore

Inside cheeks, lips or tongue.

Pain on eating

Especially spicy or acidic food.

Recurring ulcers

Some people get them often.

Non-healing ulcer

Lasting over three weeks: see a doctor.

Causes & Risk Factors

Biological Causes

Damage to the mouth lining from injury, immune reactions or deficiencies.

Key Risk Factors

  • Injury Biting the cheek or sharp teeth.
  • Deficiencies Iron, B12 and folate.
  • Stress and hormones Can trigger ulcers.

Management & Treatment

01. Pain relief

Numbing gels and salt-water rinses.

02. Avoid triggers

Spicy, acidic and sharp foods.

03. Check for causes

Blood tests if ulcers keep coming back.

Frequently Asked Questions

Are mouth ulcers contagious?
Common ulcers aren't.
When should I worry?
If an ulcer lasts more than three weeks or bleeds.

Sources and further reading

Last updated 21 October 2026. For more detail, see these trusted health organisations.