Mouth Ulcers and Sores: Causes, Symptoms & Treatment

What Are the Symptoms of Mouth Ulcers?

Mouth ulcers typically cause painful, round or oval sores on the inner cheeks, lips, gums, or tongue. Common symptoms include redness or white patches on the mucosa, burning or stinging sensations, swelling, and difficulty eating or drinking. The severity varies widely from minor discomfort to significant pain that affects daily activities.

Mouth ulcers and sores present with a range of symptoms that can significantly impact quality of life. The oral mucosa, which is the soft tissue lining the inside of your mouth, becomes damaged and forms an open wound that exposes the nerve endings underneath. This is why even small ulcers can cause considerable discomfort, particularly when eating, drinking, or speaking.

The appearance of mouth ulcers can vary depending on their cause, but they generally share certain characteristics. Most appear as round or oval lesions with a clearly defined border. The center is often white, gray, or yellowish, surrounded by a red, inflamed halo. This coloration results from the formation of a fibrin membrane over the damaged tissue and the inflammatory response of the surrounding healthy mucosa.

Understanding the typical symptoms helps distinguish between different types of mouth sores and identify when professional evaluation is needed. While most mouth ulcers are benign and self-limiting, certain warning signs indicate the need for medical attention.

Common Symptoms Include

• Painful sores: One or more open wounds in the mouth that hurt, especially when touched or when eating
• Burning or stinging: A persistent burning sensation in the affected area, often worsening with acidic or spicy foods
• Redness and swelling: Inflammation of the mucosa around the ulcer site
• White or grayish patches: A pale coating covering the ulcer center
• Difficulty eating: Pain that makes chewing and swallowing uncomfortable
• Sensitivity to certain foods: Increased discomfort with hot, spicy, acidic, or salty foods

Symptoms That Require Medical Attention

While most mouth ulcers are harmless, certain symptoms warrant prompt medical evaluation. High fever accompanying mouth sores may indicate a more serious infection requiring treatment. Difficulty breathing or swallowing is an emergency that needs immediate medical care. Large ulcers, multiple simultaneous ulcers, or ulcers that spread rapidly should be examined by a healthcare provider.

Additionally, if you have a weakened immune system due to conditions like HIV/AIDS, cancer treatment, or immunosuppressive medications, any mouth ulcer should be evaluated promptly as it may indicate a more serious underlying infection.

What Are the Different Types of Mouth Ulcers?

The main types of mouth ulcers include canker sores (aphthous ulcers), which are the most common and not contagious; oral herpes caused by the herpes simplex virus; oral thrush from fungal infection; and oral lichen planus, an inflammatory condition. Each type has distinct characteristics, causes, and treatment approaches.

Understanding the different types of mouth ulcers is essential for proper management. While they may look similar, the underlying causes vary significantly, affecting both treatment options and prognosis. Healthcare providers use the appearance, location, accompanying symptoms, and patient history to differentiate between these conditions.

Canker Sores (Aphthous Ulcers)

Canker sores, medically known as aphthous ulcers, are the most common type of mouth ulcer, affecting approximately 20% of the general population. These painful sores develop on the soft tissues inside the mouth, including the inner cheeks, lips, tongue, soft palate, and base of the gums. Unlike cold sores, canker sores are not contagious and do not appear on the external lip surface.

The exact cause of canker sores remains unclear, but several factors contribute to their development. Stress, minor mouth injuries, acidic foods, hormonal changes, and nutritional deficiencies (particularly vitamin B12, iron, and folate) can trigger outbreaks. Some people have frequent recurrences, while others experience only occasional ulcers.

Canker sores typically appear as round or oval lesions up to 5 millimeters in diameter with a white or yellowish center and a red border. Most heal within one to two weeks without scarring. Larger ulcers (major aphthous ulcers) can exceed 1 centimeter and may take several weeks to heal, sometimes leaving scars.

Oral Herpes (Cold Sores)

Oral herpes is caused by the herpes simplex virus (HSV), most commonly HSV-1. The initial infection often occurs during childhood or adolescence and may cause widespread sores throughout the mouth, accompanied by fever and general malaise. After the initial infection, the virus remains dormant in nerve cells and can reactivate periodically.

Unlike canker sores, oral herpes is highly contagious and can spread through direct contact such as kissing or sharing utensils. The virus typically causes clusters of small, fluid-filled blisters that eventually burst and form shallow ulcers. These sores most commonly appear on the lips and around the mouth but can affect the gums, palate, and tongue.

Triggers for herpes reactivation include stress, sun exposure, illness, fatigue, and hormonal changes. While the virus cannot be cured, antiviral medications can reduce symptom severity and duration if taken early in an outbreak.

Oral Thrush (Candidiasis)

Oral thrush is a fungal infection caused by Candida species, most commonly Candida albicans. This yeast naturally exists in the mouth but can overgrow under certain conditions, leading to infection. Risk factors include antibiotic use, corticosteroid medications, dry mouth, diabetes, weakened immune system, and wearing dentures.

The infection appears as creamy white patches on the tongue, inner cheeks, roof of the mouth, and throat. These patches can be scraped off, revealing red, raw tissue underneath that may bleed slightly. Some people experience a burning sensation, altered taste, or difficulty swallowing.

Oral thrush is particularly common in infants, where it appears as white patches on the tongue and cheeks. In babies, the condition usually resolves without treatment, but adults typically require antifungal medication.

Oral Lichen Planus

Oral lichen planus is a chronic inflammatory condition affecting the mucous membranes of the mouth. The condition causes lacy white lines, patches, or redness on the inner cheeks, gums, tongue, and other oral tissues. In some cases, painful ulcers develop, making eating and drinking uncomfortable.

The exact cause of oral lichen planus is unknown, but it appears to be an immune-mediated condition. Triggers may include certain medications, hepatitis C infection, and allergens in dental materials. The condition tends to wax and wane over time, with periods of remission and flare-ups.

Foods that are acidic, spicy, or hot may worsen symptoms. Management focuses on reducing inflammation and pain, typically with topical corticosteroids during flare-ups.

What Causes Mouth Ulcers and Sores?

Mouth ulcers can be caused by numerous factors including minor injuries from biting the cheek or hard toothbrush bristles, viral infections (herpes), fungal infections (thrush), bacterial infections, nutritional deficiencies (iron, B12, folate), stress, hormonal changes, certain medications, and autoimmune conditions. Often, the exact cause cannot be determined.

The oral cavity is a complex environment that must withstand constant mechanical stress from chewing and speaking while maintaining protection against numerous microorganisms. The mucous membrane lining the mouth contains nerve endings that sense pain, touch, and temperature, as well as saliva-producing glands that help keep the tissues moist and protected. When this protective barrier is breached, an ulcer forms.

Understanding the underlying causes of mouth ulcers helps guide appropriate treatment and prevention strategies. While some causes are readily identifiable, such as physical trauma, others require medical investigation to diagnose properly.

Physical Trauma and Injury

Minor injuries to the mouth are among the most common causes of ulcers. Accidentally biting your cheek, lip, or tongue while eating or talking can damage the mucosa and lead to ulcer formation. Similarly, ill-fitting dentures, orthodontic braces, or rough-edged teeth can cause repeated irritation that develops into sores.

Using a hard-bristled toothbrush or brushing too vigorously can also damage the delicate oral tissues. Even certain foods with sharp edges, such as chips or crusty bread, can scratch the mucosa and initiate ulcer formation.

Infections

Various infectious agents can cause mouth ulcers. Viral infections, particularly herpes simplex virus, are a common cause of recurring mouth sores. The initial herpes infection often causes widespread ulcers throughout the mouth, while subsequent outbreaks typically affect the lips and surrounding areas.

Fungal infections, especially candidiasis (thrush), occur when the balance of microorganisms in the mouth is disrupted. This commonly happens after antibiotic treatment, with corticosteroid use, or in people with weakened immune systems. Bacterial infections can also cause mouth sores, particularly in people with poor oral hygiene or compromised immunity.

Nutritional Deficiencies

Deficiencies in certain vitamins and minerals are associated with increased risk of mouth ulcers. Iron deficiency, vitamin B12 deficiency, and folate deficiency have all been linked to recurrent aphthous ulcers. A simple blood test can identify these deficiencies, and supplementation often reduces ulcer frequency.

Iron plays a crucial role in maintaining healthy mucous membranes, while B vitamins are essential for cell renewal and tissue repair. Ensuring adequate intake of these nutrients through diet or supplements may help prevent recurrent ulcers in susceptible individuals.

Stress and Hormonal Factors

Emotional stress is a well-recognized trigger for mouth ulcers in susceptible individuals. The exact mechanism is not fully understood, but stress affects immune function and may alter the oral environment in ways that promote ulcer formation. Many people notice that their ulcers tend to appear during particularly stressful periods.

Hormonal fluctuations, particularly during menstruation, pregnancy, or menopause, can also influence ulcer development. Some women report cyclical patterns of ulcer occurrence related to their menstrual cycle.

Medications and Medical Treatments

Certain medications can cause mouth ulcers as a side effect. Non-steroidal anti-inflammatory drugs (NSAIDs), beta-blockers, and some chemotherapy drugs are among the medications associated with oral ulcers. If you suspect a medication is causing mouth problems, consult your healthcare provider before making any changes to your treatment.

Radiation therapy to the head and neck region commonly causes oral mucositis, a condition characterized by inflammation and ulceration of the mouth lining. This side effect typically resolves after treatment completion but may require supportive care during therapy.

When Should You See a Doctor for Mouth Ulcers?

Consult a healthcare provider if mouth ulcers persist for more than 2-3 weeks, you have difficulty eating or drinking, ulcers keep recurring frequently, you have fever or feel generally unwell, you have a weakened immune system, ulcers are unusually large or numerous, or you experience symptoms like spreading, bleeding, or severe pain.

While most mouth ulcers are harmless and resolve without medical intervention, certain situations warrant professional evaluation. Knowing when to seek care helps ensure that potentially serious conditions are identified and treated promptly while avoiding unnecessary medical visits for self-limiting problems.

The two-week rule is a useful guideline: any mouth ulcer that fails to heal within two to three weeks should be evaluated by a healthcare provider. Persistent ulcers may indicate underlying conditions that require specific treatment, and in rare cases, they can be a sign of oral cancer, which has a much better prognosis when detected early.

Contact a Healthcare Provider If

• Ulcers last more than 2 weeks: Persistent sores need evaluation to rule out underlying conditions
• Eating becomes difficult: Pain severe enough to prevent adequate nutrition requires treatment
• Ulcers recur frequently: Regular outbreaks may indicate an underlying cause that can be addressed
• You have immune system problems: Immunocompromised individuals need prompt evaluation of any oral lesions
• You are pregnant: Special considerations apply during pregnancy
• The ulcer is unusually large: Major ulcers may need specific treatment
• You develop fever or feel unwell: Systemic symptoms suggest infection requiring treatment

Special Considerations for Dental Problems

If you suspect your mouth problems are related to dental issues such as ill-fitting dentures, sharp teeth, or dental materials, contact your dentist. They can examine your teeth and oral appliances to identify and correct any sources of irritation. Sometimes adjusting a denture or smoothing a rough tooth edge can prevent recurring ulcers.

What Can You Do at Home for Mouth Ulcers?

Home care for mouth ulcers includes using a soft toothbrush, choosing mild toothpaste for sensitive mouths, rinsing with salt water or antiseptic mouthwash, avoiding irritating foods (spicy, acidic, salty), eating soft foods, applying over-the-counter protective gels, and using pain-relieving products. Good oral hygiene is essential for healing.

Most mouth ulcers heal on their own within one to two weeks, but self-care measures can help reduce discomfort and promote healing. The goal of home treatment is to protect the ulcer from further irritation, manage pain, and create conditions that support the body's natural healing process.

Maintaining good oral hygiene is crucial, but it must be balanced with avoiding trauma to the affected area. Gentle care helps prevent secondary bacterial infection while allowing the ulcer to heal.

Oral Hygiene Adjustments

Switch to a soft-bristled toothbrush if you haven't already, and brush gently around the ulcer area. Hard bristles and aggressive brushing can worsen existing ulcers and potentially cause new ones. Consider using a toothpaste formulated for sensitive mouths, as some people find that sodium lauryl sulfate (SLS), a foaming agent in many regular toothpastes, irritates ulcers.

Rinsing with salt water (one teaspoon of salt in a cup of warm water) several times a day can help keep the area clean and may promote healing. Alternatively, antiseptic mouthwashes can reduce bacterial load and prevent secondary infection. Avoid alcohol-based mouthwashes, which can sting and irritate ulcers.

Dietary Modifications

Certain foods can aggravate mouth ulcers and should be avoided during healing. Acidic foods like citrus fruits, tomatoes, and vinegar-based products can cause significant stinging. Spicy foods, salty snacks, and very hot beverages also tend to worsen discomfort. Hard, crunchy foods may physically irritate the ulcer.

Instead, focus on soft, mild foods that are easy to eat. Soups, yogurt, smoothies, mashed potatoes, and soft pasta are good choices. Cool or room-temperature foods and drinks are generally better tolerated than hot ones. Using a straw for beverages can help them bypass the ulcer area.

Over-the-Counter Products

Several types of over-the-counter products can help manage mouth ulcer symptoms. Protective gels and ointments create a barrier over the ulcer, shielding it from irritation and allowing healing. Some products contain pain-relieving ingredients that provide temporary numbing. Antiseptic rinses help keep the area clean.

For dry mouth, which can worsen mouth ulcers, saliva-stimulating products such as lozenges or chewing gum may help. Saliva substitutes in gel or spray form are available for more severe dryness. Ask your pharmacist for recommendations based on your specific symptoms.

How Are Mouth Ulcers Treated?

Treatment depends on the cause. For common ulcers, topical corticosteroids, protective gels, and antiseptic rinses are used. Viral infections like herpes may need antiviral medications. Fungal infections require antifungal treatment. Oral lichen planus is managed with corticosteroids. Addressing underlying causes like nutritional deficiencies or poorly fitting dental appliances is essential.

The treatment of mouth ulcers depends on identifying the underlying cause whenever possible. While many ulcers require only symptomatic treatment, some conditions need specific medical therapy. A healthcare provider can help determine the appropriate treatment approach based on the type of ulcer, its severity, and any contributing factors.

It's important to understand that no treatment will instantly heal a mouth ulcer. The goal of medical treatment is to reduce symptoms, prevent complications, shorten healing time, and address any underlying causes that might lead to recurrence.

Topical Treatments

Topical corticosteroids are the first-line treatment for many types of mouth ulcers, particularly recurrent aphthous ulcers. These medications reduce inflammation and pain, potentially speeding healing. They come in various forms including gels, pastes, and rinses. Stronger preparations require a prescription, while milder versions may be available over the counter in some countries.

Topical anesthetics containing lidocaine or benzocaine provide temporary pain relief by numbing the affected area. These are particularly useful before meals to make eating more comfortable. Protective pastes and films create a physical barrier over the ulcer, shielding it from irritation.

Treatment for Oral Herpes

Oral herpes is treated with antiviral medications, most commonly acyclovir, valacyclovir, or famciclovir. These drugs work best when started early in an outbreak, ideally at the first sign of symptoms such as tingling or burning. For severe or frequent outbreaks, daily suppressive therapy may be recommended.

Over-the-counter topical treatments may provide some symptom relief but are generally less effective than prescription oral antivirals. For severe primary herpes infections, particularly in children or immunocompromised individuals, hospitalization and intravenous antiviral therapy may be necessary.

Treatment for Oral Thrush

Fungal infections of the mouth are treated with antifungal medications. Mild cases may respond to antifungal mouth rinses containing nystatin. More severe or persistent infections may require oral fluconazole tablets. Treatment duration varies but typically continues for at least a week after symptoms resolve to prevent recurrence.

For denture wearers with thrush, treating both the infection and the dentures is essential. Dentures harbor fungal organisms and must be thoroughly cleaned and disinfected to prevent reinfection.

Treatment for Oral Lichen Planus

Oral lichen planus cannot be cured, but symptoms can be managed effectively. Topical corticosteroids are the mainstay of treatment during flare-ups. In severe cases, systemic corticosteroids or other immunomodulating medications may be needed. Good oral hygiene and avoiding triggers help reduce flare-ups.

Addressing Underlying Causes

If nutritional deficiencies are identified, supplementation with iron, vitamin B12, or folate may reduce ulcer frequency. Poorly fitting dentures or dental appliances should be adjusted or replaced. If medications are suspected of causing ulcers, alternative drugs may be considered under medical supervision.

For patients who grind their teeth or clench their jaws (bruxism), a dental night guard may help prevent bite injuries to the mouth. Stress management techniques may benefit those whose ulcers seem to correlate with stressful periods.

How Can You Prevent Mouth Ulcers?

Prevention strategies include maintaining good oral hygiene with a soft toothbrush, avoiding foods that trigger ulcers, managing stress, ensuring adequate nutrition (especially iron, B12, and folate), staying hydrated, avoiding tobacco products, and addressing dental issues like sharp teeth or ill-fitting dentures promptly.

While not all mouth ulcers can be prevented, many recurrences can be reduced or avoided by identifying and addressing contributing factors. People who experience frequent ulcers often benefit from keeping a diary to track potential triggers, including foods, stress levels, sleep patterns, and other factors that may correlate with outbreaks.

Prevention strategies focus on maintaining a healthy oral environment, avoiding known triggers, and addressing underlying health issues that may contribute to ulcer formation.

Oral Care Best Practices

Using a soft-bristled toothbrush and brushing gently helps protect the oral mucosa from damage. Replacing your toothbrush regularly (every three months or when bristles become frayed) ensures effective cleaning without excessive abrasion. Some people benefit from SLS-free toothpaste, as this ingredient can irritate sensitive tissues.

Regular dental check-ups allow identification of potential problems such as sharp tooth edges, rough fillings, or poorly fitting dental appliances before they cause ulcers. Prompt attention to any dental discomfort can prevent chronic irritation.

Dietary Considerations

If certain foods consistently trigger your ulcers, avoiding them is sensible. Common culprits include acidic fruits, tomatoes, chocolate, nuts, and coffee, though triggers vary between individuals. Maintaining adequate hydration helps keep the mouth moist and the mucosa healthy.

A balanced diet providing sufficient vitamins and minerals supports oral health. If you follow a restricted diet (vegetarian, vegan, or due to food allergies), pay particular attention to nutrients like vitamin B12 and iron, which may be harder to obtain.

Lifestyle Factors

Tobacco use, whether smoking or smokeless tobacco, damages the oral mucosa and increases the risk of mouth sores and other oral health problems. Quitting tobacco benefits oral health among many other health improvements.

Stress management through techniques such as exercise, meditation, adequate sleep, and work-life balance may help reduce stress-related ulcers. While eliminating stress entirely is unrealistic, developing healthy coping mechanisms can reduce its physical manifestations.

How Are Mouth Ulcers Diagnosed?

Diagnosis typically begins with clinical examination of the mouth. Healthcare providers assess the ulcer's appearance, location, duration, and associated symptoms. Blood tests may check for nutritional deficiencies or underlying conditions. A biopsy (small tissue sample) may be taken for persistent ulcers to rule out serious conditions.

Most mouth ulcers can be diagnosed based on clinical appearance and patient history. The healthcare provider will examine your mouth, noting the size, shape, number, and location of ulcers. They will ask about how long the ulcers have been present, associated symptoms, potential triggers, and any previous episodes.

For persistent, recurrent, or unusual-appearing ulcers, additional investigations may be needed to identify underlying causes or rule out more serious conditions.

Clinical Examination

A thorough oral examination is the first step in diagnosis. The healthcare provider will examine all surfaces of your mouth, including the cheeks, gums, tongue, palate, and throat. They may also examine your lymph nodes and check for signs of systemic illness.

The appearance of the ulcer provides important diagnostic clues. Aphthous ulcers have a characteristic round or oval shape with a white center and red border. Herpes lesions typically appear as clusters of small blisters that later ulcerate. Thrush presents as white patches that can be scraped off.

Laboratory Tests

Blood tests may be ordered to check for nutritional deficiencies (iron, vitamin B12, folate), blood disorders, or markers of systemic diseases. If infection is suspected, a swab or culture may be taken to identify the causative organism.

For suspected fungal infections, a sample may be examined under a microscope or cultured to confirm the diagnosis and guide treatment selection.

Biopsy

For ulcers that persist despite treatment, appear unusual, or raise concern for serious conditions, a biopsy may be recommended. This involves removing a small sample of tissue for microscopic examination. The procedure is usually done under local anesthesia and is typically not painful.

Biopsy helps distinguish between benign conditions and more serious problems, including oral cancer. While cancer is an uncommon cause of mouth ulcers, early detection significantly improves treatment outcomes.