Mouth Ulcers – A Helpful Guide to Causes, Treatment & Prevention

Mouth ulcers are a common oral health issue that most people will experience at some point in their lives. Painful, annoying and sometimes recurrent, these small sores can make eating, speaking and daily life uncomfortable. In this guide we cover everything you need to know about mouth ulcers — from what causes them, to how best to treat them, and when to see your dentist.

What Are Mouth Ulcers?

A mouth ulcer is a sore or break in the mucous membrane lining the mouth. They often appear as small, shallow lesions with a white or yellow-grey centre and a red border. Although they can develop anywhere inside the mouth, such as on the lips, cheeks, gums, tongue, or soft palate, they’re not contagious and usually heal on their own.

Typically, most mouth ulcers resolve within 7–14 days without medical intervention. However, some may persist longer, recur frequently, or cause significant pain.

According to HSE, "They're rarely a sign of anything serious but may be uncomfortable."

Common Causes of Mouth Ulcers

The exact cause of mouth ulcers isn’t always clear, but several factors can trigger their development:

1. Minor Mouth Injury - biting the inside of the cheek, aggressive tooth brushing or irritation from braces or a sharp filling can create small wounds that turn into ulcers.

2. Stress and Hormonal Factors - stress, tiredness and hormonal changes (such as during menstruation) are often linked to recurring ulcers.

3. Nutritional Deficiencies - deficiencies in vitamin B12, folic acid, iron or other nutrients may increase the risk of canker sores.

4. Toothpaste Ingredients - toothpaste containing sodium lauryl sulphate (SLS) can sometimes irritate the lining of the mouth and contribute to ulcer formation.

5. Underlying Health Conditions - underlying illnesses — such as viral infections (e.g., hand, foot and mouth disease) or autoimmune conditions — can also cause mouth ulcers.

Symptoms to Look Out For

Mouth ulcers are usually easy to spot. Key symptoms include:

• A sore or painful spot inside the mouth

• Round or oval lesions with a pale centre

• Pain that increases when eating acidic, spicy or sharp foods

• Discomfort that lasts longer than two weeks

If a sore is unusually large, extremely painful or doesn’t heal within three weeks, you should seek advice from a healthcare professional, as it could indicate a more serious condition.

How Are Mouth Ulcers Treated?

Generally, most mouth ulcers don’t need prescription treatment and will heal naturally with time. However, there are effective ways to manage discomfort and support the healing process.

Self-Care Measures

• Rinse with warm salt water a few times a day

• Avoid spicy, acidic or crunchy foods until healing occurs

• Drink plenty of fluids and stay well hydrated

• Brush with a soft-bristled toothbrush and gentle fluoride toothpaste

Medicinal Treatments

Over-the-counter gels, mouth rinses or protective pastes can ease pain and shield the ulcer from irritation. In severe or persistent cases, a dentist or GP may prescribe steroid pastes or other medications to reduce inflammation.

When to See a Dentist

You should book an appointment with a dental professional if:

• A mouth ulcer lasts longer than three weeks

• Ulcers recur frequently

• The sore grows in size or pain worsens

• You have other worrying symptoms such as unexplained weight loss, bleeding, or lumps

At The Dental Suite, we can examine persistent mouth ulcers, rule out more serious causes and recommend appropriate treatment. Explore our general dentistry and examination services to learn how we can help.

Preventing Mouth Ulcers

While it’s not always possible to prevent them entirely, you can reduce your likelihood of developing mouth ulcers by:

Maintain Excellent Oral Hygiene

Brush twice a day, floss daily and visit your dentist regularly for check-ups and cleans.

Watch Your Diet

Avoid known food triggers and maintain a balanced diet rich in vitamins and minerals to support oral and overall health.

Use Gentle Oral Care Products

Choose toothpaste and mouthwash without harsh detergents like SLS and avoid products with strong alcohol content.

Manage Stress & Lifestyle

Stress-reduction techniques, adequate sleep and good hydration can all help lower ulcer risk.

Supporting Your Oral Health

If mouth ulcers are causing you discomfort or you’re concerned about recurrent sores, our expert team at The Dental Suite is here for you. We offer comprehensive oral health assessments, hygiene appointments and personalised advice to keep your mouth healthy and comfortable.

Discover how we care for your smile:

Dental Hygiene & General Dentistry

How Often Should You Visit the Dentist?

Key Takeaways

• Mouth ulcers are common, painful sores that usually heal on their own within 1–2 weeks.

• Causes include minor injury, stress, nutritional deficiencies and certain oral products.

• Self-care, diet changes and good oral hygiene can speed healing and reduce discomfort.

• If ulcers persist, recur or worsen, professional dental advice is recommended.