Mouth ulcers (also called canker sores) arise from a variety of triggers rather than a single cause. They are usually harmless and resolve on their own, but recurrent or persistent ulcers merit evaluation. Key factors that can contribute
- Local injury or irritation
- Biting the inside of the cheek, cheek rubbing from braces, dentures, or sharp teeth, and aggressive brushing or irritating toothpaste.
- Burns from hot foods or drinks, or contact with harsh mouthwashes.
- Minor infections or illnesses
- Viral infections (such as herpes simplex) can cause painful ulcers in or around the mouth.
- Gastrointestinal conditions (e.g., inflammatory bowel disease, coeliac disease) can be associated with mouth ulcers in some people.
- Nutritional deficiencies
- Low levels of iron, folate (vitamin B9), or vitamin B12 can predispose to ulcers, especially if they occur repeatedly.
- Hormonal changes and stress
- Stress, fatigue, and hormonal fluctuations (e.g., pregnancy) are commonly linked with episodes.
- Medications and medical conditions
- Some medications (for example, NSAIDs, beta-blockers, certain cancer therapies) can trigger ulcers.
- Autoimmune or systemic diseases (such as Behçet’s disease or lupus) can present with recurrent mouth ulcers.
- Allergies or sensitivities
- Allergic reactions to certain foods, toothpastes, or flavoring agents can occasionally provoke ulcers.
What to do about common, non-serious ulcers
- Guard against trauma: use a soft-bristled toothbrush, avoid sharp-edged dental work, and ensure dentures/braces fit well.
- Gentle care: rinse with a saltwater solution or a non-irritating mouthwash; avoid alcohol-containing or highly acidic products.
- Oral hygiene: maintain good overall dental hygiene to prevent secondary infection.
- Identify triggers: track if ulcers correlate with stress, illness, new medications, or dietary changes.
- Nutritional check: ensure adequate intake of iron, folate, and vitamin B12 through diet or supplements if advised by a clinician.
When to seek medical evaluation
- Ulcers lasting more than two weeks or spreading, or are unusually large or painful.
- Recurrent ulcers that interrupt daily activities or are accompanied by fever, mouth swelling, or skin/eye symptoms.
- If there is a known underlying condition (e.g., inflammatory bowel disease, diabetes) or if taking medications known to cause ulcers.
- Ulcers in very young children, older adults with systemic illness, or with signs suggesting infection or immune compromise.
Diagnosis and next steps
- A clinician will usually review history, exam the mouth, and may order blood tests to assess iron, folate, or vitamin B12 levels, as well as screen for underlying conditions if indicated.
- In persistent or atypical cases, a biopsy or referral to a dentist/oral medicine specialist may be recommended.
If you’d like, share:
- Age and any existing health conditions
- How long the ulcers have persisted
- Any accompanying symptoms (fever, skin rashes, eye symptoms)
- Current medications or recent changes
- Dietary changes or stress levels
This information can help tailor advice and determine whether a routine at- home approach or clinical evaluation is needed.
