Mouth Ulcers (Aphthous Ulcers): Causes, Treatment and Prevention

What Are Mouth Ulcers (Aphthous Ulcers)?

These oral lesions can develop anywhere on the soft mucosal tissues — the inner cheeks, inner lips, tongue, floor of the mouth, soft palate, and gums. They range from mildly uncomfortable to severely painful depending on their size, depth, and location.

Aphthous ulcers typically begin as a tingling or burning sensation before a visible sore appears. The ulcer itself has a characteristic look: a round or oval depression with a white, yellow, or greyish centre surrounded by a distinct red, inflamed border. They are soft and tender to the touch, and even light contact with food, a toothbrush, or the tongue can trigger a sharp sting.

Most people experience an occasional mouth ulcer at some point in their life. These isolated episodes usually resolve quickly and do not indicate an underlying problem. Recurrent aphthous stomatitis, on the other hand, refers to a pattern of repeated outbreaks — sometimes with new ulcers appearing before previous ones have fully healed. This cyclical pattern often has identifiable triggers that, once understood, can be managed to reduce the frequency and severity of episodes.

It is important to distinguish aphthous ulcers from cold sores. Cold sores are caused by the herpes simplex virus and typically appear on or around the lips as fluid-filled blisters. They are contagious, whereas aphthous ulcers occur inside the mouth, are not caused by a virus, and cannot be spread to others.

What Causes Mouth Ulcers?

The exact cause of aphthous ulcers is not fully understood, but research has identified a range of triggers that can provoke outbreaks. Most cases involve a combination of factors rather than a single cause.

Minor Injury and Trauma

Physical damage to the delicate oral lining is one of the most common triggers. Accidental cheek or lip biting, scratching from sharp or crunchy foods, vigorous tooth brushing, and irritation following dental procedures can all create the initial break in the tissue that develops into an ulcer.

Ill-fitting dentures, rough edges on broken teeth, and orthodontic appliances such as braces can also cause persistent rubbing against the cheek or lip lining, leading to recurrent ulceration in the same area.

Stress and Fatigue

Emotional stress and physical exhaustion are well-documented triggers for mouth ulcers. Stressful periods — such as exams, work deadlines, or personal difficulties — frequently coincide with outbreaks in susceptible individuals. Stress affects the immune system and the body's inflammatory response, making the oral tissues more vulnerable to ulceration.

Dietary Triggers

Certain foods can provoke or worsen mouth ulcers in sensitive individuals. Common culprits include acidic fruits such as oranges, lemons, and tomatoes, along with spicy foods, chocolate, and coffee. Some people also find that wheat or gluten-containing foods trigger outbreaks, particularly those with an undiagnosed sensitivity.

Vitamin and Mineral Deficiencies

Nutritional shortfalls are a significant contributor to recurrent oral ulceration. Deficiencies in vitamin B12, iron, folic acid, and zinc have all been linked to increased susceptibility. These nutrients play essential roles in maintaining healthy mucosal tissue and supporting immune function. When levels are low, the oral lining becomes more fragile and slower to heal.

Hormonal Changes

Some women experience a pattern of mouth ulcers that correlates with their menstrual cycle. Outbreaks may occur in the days before or during menstruation, suggesting that hormonal fluctuations influence mucosal tissue vulnerability. This pattern often improves during pregnancy and after menopause, further supporting the hormonal link.

Medical Conditions

Recurrent aphthous ulcers can be associated with certain systemic conditions. Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, coeliac disease, Behçet's disease, and various immune system disorders are all linked to an increased frequency of oral ulceration. In these cases, the ulcers are one manifestation of a broader inflammatory process.

Medications

Certain medications list mouth ulcers among their side effects. These include some non-steroidal anti-inflammatory painkillers, beta-blockers used for heart conditions, nicorandil (a medication for angina), and chemotherapy drugs. If you notice ulcers developing after starting a new medication, discuss this with your prescribing clinician.

Genetic Predisposition

Family history plays a role in susceptibility to aphthous ulcers. If one or both parents experience recurrent mouth ulcers, their children are more likely to develop them as well. This genetic component means that some individuals are inherently more prone to outbreaks regardless of other triggers.

Types of Mouth Ulcers

Aphthous ulcers are classified into three types based on their size, appearance, and healing behaviour. Understanding which type you have helps set realistic expectations for how long they will last and whether professional treatment may be beneficial.

Minor Aphthous Ulcers

These are by far the most common type, accounting for approximately 80 per cent of all aphthous ulcers. Minor aphthae are small, typically less than five millimetres in diameter, and oval in shape. They appear on the inner cheeks, lips, tongue, or floor of the mouth.

• Heal within 10 to 14 days without any specific treatment
• Do not leave scarring once healed
• Painful but manageable with self-care measures

Major Aphthous Ulcers

Major aphthae are larger, often exceeding one centimetre in diameter, and penetrate deeper into the tissue. They are significantly more painful than minor ulcers and can make eating, drinking, and speaking very uncomfortable.

• May take several weeks or occasionally months to heal completely
• Can leave scarring due to the depth of tissue damage
• Often require professional management to control pain and promote healing

Herpetiform Ulcers

Despite their name, herpetiform ulcers are not caused by the herpes virus. They present as clusters of multiple tiny, pinhead-sized sores that may merge together to form larger irregular ulcers. They tend to appear on the tongue and floor of the mouth.

• Typically heal within 7 to 14 days without scarring
• Less common than minor or major types
• The clustered appearance can be alarming, but they are not contagious

Symptoms of Mouth Ulcers

The symptoms of aphthous ulcers are usually straightforward to recognise. Most people can identify a mouth ulcer by its appearance and the discomfort it causes, though the severity varies depending on the type and location.

• Pain or discomfort — a sharp, stinging pain when eating, drinking, or talking, particularly with salty, spicy, or acidic foods and drinks
• Burning or tingling sensation — often felt one to two days before the ulcer becomes visible, serving as an early warning sign
• Visible sores — round or oval depressions with a white, yellow, or grey centre that are clearly different from the surrounding pink tissue
• Red inflamed border — the tissue immediately surrounding the ulcer appears redder and more swollen than normal
• Localised swelling — the area around the ulcer may feel raised or puffy, adding to the sensation of something being in the way
• Difficulty eating — ulcers on the tongue, inner cheeks, or gums can make chewing uncomfortable, particularly with rough or textured foods
• Irritation from brushing — contact with a toothbrush can be painful, sometimes causing people to avoid brushing near the affected area

How Long Do Mouth Ulcers Last?

The duration of a mouth ulcer depends on its type and severity. Understanding the typical healing timeline helps you know when an ulcer is following a normal course and when it may warrant professional attention.

• Minor aphthous ulcers — 7 to 14 days. Pain is usually most intense during the first three to four days, then gradually eases as the ulcer begins to heal from the edges inward
• Major aphthous ulcers — several weeks to months. These deeper ulcers heal more slowly and may leave a scar. Professional treatment can help manage pain and support the healing process
• Herpetiform ulcers — 7 to 14 days. Although they appear in clusters, individual sores within the group tend to heal relatively quickly

The healing stages generally follow a predictable pattern. The ulcer first appears as a tingling sensation, followed by a visible white or yellow sore with a red border. Over the next few days, the ulcer reaches its maximum size and pain peaks. After this, the edges begin to contract and the surrounding redness fades. New tissue gradually covers the area until the surface is smooth and pain-free.

Several factors can slow healing, including continued trauma to the area (such as biting or irritation from braces), poor nutrition, high stress levels, smoking, and underlying health conditions. Keeping the area clean and avoiding further irritation gives the ulcer the best chance of healing within the expected timeframe.

When to See a Dentist About Mouth Ulcers

Most mouth ulcers resolve on their own and do not require professional treatment. However, there are clear indicators that a dental assessment is advisable to rule out other conditions and explore management options.

• Persists longer than three weeks — any mouth ulcer that has not healed after three weeks should be examined by your dental team
• Unusually large or painful — ulcers significantly larger than normal or causing severe pain that prevents eating deserve assessment
• Frequent recurrence — if new ulcers keep appearing before previous ones heal, or you experience several outbreaks a year
• Difficulty eating or drinking — when ulcers interfere with adequate nutrition or hydration
• Fever or systemic symptoms — ulcers accompanied by fever, fatigue, or feeling generally unwell
• Spreading or worsening — ulcers that are growing in size, number, or severity despite self-care
• Associated skin or eye symptoms — ulcers occurring alongside skin rashes, genital sores, or eye inflammation may indicate a systemic condition

Diagnosis and Assessment

Diagnosing aphthous ulcers is primarily based on clinical observation and a thorough discussion of your history. Your dental team will conduct a structured assessment to understand your symptoms and identify any contributing factors.

• Medical history review — discussing how often ulcers occur, how long they last, any known triggers, current medications, and whether you have any associated medical conditions
• Visual examination — inspecting the ulcer's size, shape, location, and appearance to determine the type and assess whether it looks consistent with an aphthous ulcer or could indicate another condition
• Oral health assessment — checking for potential trauma sources such as sharp tooth edges, rough fillings, or ill-fitting dental appliances that could be causing or worsening the ulceration
• Discussion of patterns — identifying possible links between outbreaks and factors such as stress, diet, hormonal changes, or new medications to build a clearer picture of your personal triggers

In some cases, your dentist may recommend blood tests to check for nutritional deficiencies or underlying conditions that could be contributing to recurrent ulceration. If an ulcer has atypical features or has not responded to treatment, further assessment may be arranged to ensure an accurate diagnosis.

Treatment Options for Mouth Ulcers

Treatment for mouth ulcers focuses on four key goals: relieving pain, reducing inflammation, preventing secondary infection, and managing underlying causes to reduce recurrence. The approach depends on the severity and frequency of your ulcers.

Over-the-Counter Treatments

For occasional minor ulcers, pharmacy-available products are usually sufficient. Protective pastes and gels form a barrier over the ulcer surface, shielding it from food and saliva contact while the tissue heals beneath.

• Protective pastes and gels — applied directly to the ulcer to create a physical barrier that reduces pain during eating and speaking
• Alcohol-free mouthwashes — antimicrobial rinses help keep the ulcer clean without the stinging that alcohol-based products cause
• Pain relief gels — topical anaesthetic gels containing benzocaine or lidocaine numb the area temporarily for more comfortable eating

Prescription Treatments

When over-the-counter options are insufficient, your dental team can prescribe stronger treatments targeted at reducing inflammation and supporting healing.

• Corticosteroid pastes — prescription-strength anti-inflammatory pastes applied directly to the ulcer to reduce swelling and accelerate healing
• Antimicrobial mouthwashes — chlorhexidine-based rinses that reduce bacterial load and help prevent secondary infection of the ulcer
• Prescription pain relief — stronger topical or systemic pain relief for severe cases where eating and daily activities are significantly affected

Professional Dental Care

Your dentist can address physical causes of recurrent ulceration through targeted general dentistry interventions that eliminate the source of trauma.

• Smoothing sharp tooth edges or rough fillings that repeatedly irritate the cheek or tongue
• Adjusting dentures or orthodontic appliances to eliminate pressure points against the soft tissue
• Treating underlying dental conditions that may be contributing to oral tissue irritation

Addressing Nutritional Deficiencies

When blood tests reveal nutritional shortfalls, targeted supplementation and dietary changes can significantly reduce the frequency of recurrent aphthous ulcers.

• Vitamin B12, iron, folic acid, or zinc supplementation as indicated by test results
• Dietary adjustments to include more nutrient-rich foods that support mucosal health
• Ongoing monitoring to ensure levels return to a healthy range

Stress Management

For patients whose outbreaks correlate with stressful periods, addressing the underlying stress can be a key part of long-term management.

• Relaxation techniques such as deep breathing, mindfulness, and regular exercise
• Prioritising adequate sleep and maintaining consistent sleep routines
• Appropriate referral pathways if stress or anxiety is significantly impacting wellbeing

Home Remedies and Self-Care for Mouth Ulcers

Many mouth ulcers can be managed comfortably at home with simple, practical measures. These remedies aim to reduce pain, protect the ulcer from further irritation, and support the body's natural healing process.

• Salt water rinses — dissolve half a teaspoon of salt in a glass of warm water and gently rinse for 30 seconds, two to three times daily. This helps keep the area clean and may promote healing
• Avoid irritating foods — steer clear of spicy, acidic, salty, and rough-textured foods that contact the ulcer and intensify pain
• Use a soft toothbrush — switch to a soft-bristled brush and use gentle, careful strokes near the affected area to avoid further trauma
• Drink through a straw — using a straw allows liquids to bypass the ulcer, reducing contact with acidic or hot drinks
• Apply ice chips — holding a small ice chip against the ulcer numbs the area temporarily and reduces inflammation
• Honey application — dabbing a small amount of honey onto the ulcer provides a natural anti-inflammatory and protective coating
• Coconut oil — applying a thin layer of coconut oil can soothe the tissue and may help reduce discomfort between meals

How to Prevent Mouth Ulcers

While not all mouth ulcers can be prevented, understanding your personal triggers and taking proactive steps can significantly reduce the frequency and severity of outbreaks.

• Identify your triggers — keep a diary noting when ulcers appear and what preceded them. Over time, patterns emerge that help you avoid your personal triggers
• Gentle oral hygiene — brush with a soft-bristled toothbrush using careful strokes. Consider switching to an SLS-free toothpaste if you suspect your current product is contributing to outbreaks
• Manage stress — incorporate regular stress reduction activities into your routine, whether that is exercise, meditation, hobbies, or simply ensuring you get enough rest
• Eat a balanced diet — ensure your diet includes sufficient vitamin B12, iron, folic acid, and zinc through foods such as leafy greens, lean meats, eggs, legumes, and whole grains
• Protect your mouth during sports — wearing a mouthguard during contact sports or high-risk activities prevents the trauma that can trigger ulceration
• Regular dental check-ups — routine dental examinations allow your dentist to identify and correct potential trauma sources such as sharp teeth, rough restorations, or ill-fitting appliances before they cause recurrent ulcers

Mouth Ulcers Before and After

With the right combination of self-care, professional treatment, and trigger management, patients with recurrent mouth ulcers can experience meaningful improvements in their daily comfort and quality of life.

• Reduced pain within days — appropriate treatment brings noticeable relief quickly, allowing more comfortable eating and speaking
• Faster healing times — targeted treatment supports the body's repair process and can shorten the duration of individual episodes
• Fewer recurrent episodes — identifying and addressing underlying triggers reduces the frequency of future outbreaks
• Improved quality of life — patients report greater confidence in eating, speaking, and social interactions when ulcers are effectively managed

To see examples of how dental treatment can improve oral health and comfort, visit our smile gallery.

Are Mouth Ulcers Contagious?

Aphthous ulcers are not contagious. They cannot be passed to another person through kissing, sharing food or utensils, or any other form of close contact. This is one of the key differences between mouth ulcers and cold sores.

Cold sores are caused by the herpes simplex virus and are contagious, particularly when the blister is open and weeping. They typically appear on or around the lips, whereas aphthous ulcers occur exclusively inside the mouth on the soft mucosal lining.

If you are unsure whether a sore is an aphthous ulcer or a cold sore, your dental team can help you distinguish between them. The distinction is important because the two conditions have different causes and require different treatment approaches.

Frequently Asked Questions About Mouth Ulcers