Canker sores, also known as aphthous ulcers, are small, painful lesions that appear on the soft tissues inside your mouth. These bothersome sores can develop on the inner surfaces of your cheeks or lips, on or underneath your tongue, at the base of your gums, or even on the soft palate at the back of your mouth. Typically characterized by a white or yellowish center surrounded by a red, inflamed border, canker sores, while not contagious, can cause significant discomfort, making eating and speaking a challenge.
While they are sometimes confused with cold sores, it’s important to note that canker sores are distinct. Unlike cold sores, which are caused by the herpes simplex virus and appear on the outer lips and are contagious, canker sores occur exclusively inside the mouth and are not infectious. For most individuals, canker sores are a recurring nuisance that generally resolve on their own within one to two weeks. However, if you experience unusually large or intensely painful canker sores, or if they persist for an extended period without healing, seeking advice from your doctor or dentist is recommended.
Symptoms of Canker Sores
Canker sores typically manifest as round or oval-shaped lesions with a distinctive appearance: a white or yellow center encircled by a red, inflamed border. These sores are always located inside the mouth, appearing on areas such as:
- On or under the tongue
- Inside the cheeks or lips
- At the base of the gums
- On the soft palate
Often, individuals experience a tingling or burning sensation in the area one or two days before a canker sore visibly appears.
Canker sores are classified into several types, primarily minor, major, and herpetiform, each with distinct characteristics.
Minor Canker Sores
Minor canker sores are the most prevalent type and are characterized by:
- Small size, typically less than 1 centimeter in diameter.
- An oval shape with a clearly defined red edge.
- Healing within one to two weeks without leaving any scars.
Major Canker Sores
Major canker sores are less common and are distinguished by:
- Larger size and deeper penetration into the tissue compared to minor canker sores, often exceeding 1 centimeter.
- Generally round shape with well-defined borders, although they may exhibit irregular edges when they become very large.
- Potential to cause significant pain due to their size and depth.
- Longer healing time, potentially taking up to six weeks to resolve, and may result in scar tissue formation.
Herpetiform Canker Sores
Herpetiform canker sores, despite their name, are not related to the herpes virus. They are uncommon and tend to appear later in life. Key features include:
- Pinpoint size, typically just a few millimeters in diameter.
- Frequent occurrence in clusters, ranging from 10 to 100 small sores that can sometimes merge to form a larger, irregularly shaped ulcer.
- Irregularly defined edges.
- Healing within one to two weeks without scarring, similar to minor canker sores.
When to Seek Medical Advice for Canker Sores
While most canker sores heal naturally, it’s important to consult a doctor in the following situations:
- Unusually large canker sores: Sores that are significantly larger than typical minor canker sores.
- Recurring sores or frequent outbreaks: Experiencing canker sores that reappear frequently, with new sores developing before previous ones have healed.
- Persistent sores: Sores that last for two weeks or longer without showing signs of healing.
- Sores extending to the vermilion border: Canker sores that spread to the outer edge of the lips themselves.
- Uncontrollable pain: Pain associated with canker sores that cannot be effectively managed with over-the-counter self-care measures.
- Extreme difficulty eating or drinking: Canker sores that make it significantly challenging to eat or drink due to pain.
- High fever alongside canker sores: Developing a high fever in conjunction with a canker sore outbreak, which could indicate a secondary infection or underlying condition.
Additionally, it is advisable to see your dentist if you suspect that sharp tooth surfaces or dental appliances are contributing to the recurrence of canker sores.
What Causes Canker Sores?
The exact cause of canker sores remains elusive, but research suggests they are likely triggered by a combination of factors. It’s possible for different triggers to be at play, even in the same individual, across different outbreaks.
Common Triggers
Several factors are identified as potential triggers for canker sore development:
- Minor mouth injuries: Trauma to the mouth lining from dental work, over-vigorous tooth brushing, sports-related accidents, or accidental cheek biting.
- Sodium lauryl sulfate (SLS): Toothpastes and mouthwashes containing sodium lauryl sulfate, a common foaming agent, can contribute to canker sore outbreaks in susceptible individuals.
- Food sensitivities: Certain food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese, and spicy or acidic foods, have been linked to canker sores in some people.
- Nutritional deficiencies: A diet lacking essential nutrients such as vitamin B-12, zinc, folate (folic acid), or iron may increase the likelihood of developing canker sores.
- Allergic reactions to oral bacteria: An allergic response to certain types of bacteria naturally present in the mouth could trigger canker sore formation.
- Helicobacter pylori (H. pylori): The same bacteria responsible for peptic ulcers in the stomach has also been implicated in the development of canker sores in some studies.
- Hormonal fluctuations: Hormonal shifts, particularly during menstruation in women, can be a contributing factor in canker sore outbreaks.
- Emotional stress: Periods of increased emotional stress are frequently reported as triggers for canker sores.
Underlying Conditions
In some instances, canker sores may be a symptom of or exacerbated by underlying health conditions, including:
- Celiac disease: An autoimmune disorder characterized by sensitivity to gluten, a protein found in wheat, barley, and rye, can manifest with mouth ulcers, including canker sores.
- Inflammatory bowel diseases (IBD): Conditions like Crohn’s disease and ulcerative colitis, which cause chronic inflammation of the digestive tract, are associated with an increased risk of canker sores.
- Behcet’s disease: A rare and complex disorder that causes inflammation throughout the body, including the mouth, often presenting with painful canker sores as a primary symptom.
- Immune system dysfunction: A compromised or malfunctioning immune system that mistakenly attacks healthy cells in the mouth, rather than just pathogens, can lead to canker sore development.
- HIV/AIDS: Human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) can suppress the immune system, making individuals more susceptible to oral infections and conditions, including canker sores.
It’s crucial to reiterate that unlike cold sores, canker sores are not caused by the herpes simplex virus and are not contagious.
Risk Factors for Canker Sores
While anyone can develop canker sores, certain groups are more prone to experiencing them:
- Age: Canker sores are more frequently observed in adolescents and young adults.
- Gender: Women are statistically more likely to develop canker sores compared to men.
- Family history: Individuals with a family history of recurrent canker sores are at a higher risk. This familial tendency may be due to genetic predisposition or shared environmental factors, such as dietary habits or exposure to allergens.
Prevention Tips for Canker Sores
While canker sores often tend to recur, adopting certain preventive measures can help reduce their frequency and severity:
- Dietary awareness: Pay close attention to your diet and try to identify and avoid foods that seem to irritate your mouth or trigger outbreaks. Common culprits include nuts, chips, pretzels, certain spices, salty foods, and acidic fruits such as pineapple, grapefruit, and oranges. It’s also important to avoid any foods to which you know you have a sensitivity or allergy.
- Nutritious food choices: Maintain a balanced and healthy diet rich in fruits, vegetables, and whole grains to prevent nutritional deficiencies that may contribute to canker sore development.
- Good oral hygiene practices: Establish consistent oral hygiene habits. Brush your teeth gently after meals and floss daily to keep your mouth clean and free of food particles that could potentially trigger sores. Use a soft-bristled toothbrush to minimize irritation to delicate mouth tissues and consider switching to toothpastes and mouthwashes that are free of sodium lauryl sulfate (SLS).
- Mouth protection: If you wear braces or other dental appliances with sharp edges, consult your dentist about using orthodontic wax to cover these edges and prevent irritation to the inner mouth.
- Stress management: If you notice a correlation between stress levels and canker sore outbreaks, incorporate stress-reduction techniques into your daily routine. Practices such as meditation, deep breathing exercises, and guided imagery can be beneficial in managing stress and potentially reducing the frequency of canker sores.
By Mayo Clinic Staff
