Canker sores, also known as aphthous ulcers, are common and often painful mouth sores that develop on the soft tissues inside the mouth. These ulcers are not contagious and typically appear as shallow lesions. While their white or yellowish center might suggest pus, this is a misconception; it’s part of the body’s natural healing process.
The Distinctive Appearance of a Canker Sore
Canker sores usually appear as round or oval lesions with a characteristic white or yellowish center and a defined red border. The white or yellow material is not pus, but rather a protective layer of fibrin, a protein crucial for blood clotting and tissue repair. This fibrin membrane, sometimes called a pseudomembrane, forms over the exposed tissue as part of the body’s healing response, shielding the underlying area.
These sores can vary in size, from very small to larger ones measuring about 1/2 to 1 inch in diameter. They commonly form on the inner surfaces of the cheeks and lips, on or under the tongue, at the base of the gums, or on the soft palate. A tingling or burning sensation might precede the sore’s visible appearance by a day or two.
Distinguishing Canker Sores from Other Oral Conditions
Differentiating canker sores from other oral conditions is important for appropriate care, as their causes and treatments vary. Unlike canker sores, cold sores, also known as fever blisters, are caused by the highly contagious herpes simplex virus (HSV-1). Cold sores typically appear as fluid-filled blisters on the outside of the mouth, often around the lips, and progress to crust over. While rare, cold sores can sometimes appear inside the mouth, especially in young children.
In contrast, some bacterial or fungal infections might involve pus or other distinct symptoms. For instance, oral thrush, a fungal infection caused by Candida species, presents as creamy white, raised patches that resemble cottage cheese on the tongue, inner cheeks, or other oral surfaces. These patches may bleed if scraped and can be accompanied by soreness, a cottony feeling in the mouth, or loss of taste. Bacterial infections might lead to symptoms like fever, pain, and potentially pus, which are not typical for canker sores.
Common Causes and Triggers
The precise cause of canker sores is not fully understood, but several factors are known to trigger their development. Minor injuries to the mouth, such as accidental biting, aggressive brushing, or irritation from dental appliances like braces, are common triggers. Certain foods, particularly acidic or spicy items like citrus fruits, tomatoes, or strawberries, can also provoke canker sores.
Nutritional deficiencies, especially in vitamin B12, iron, folate, and zinc, are linked to increased susceptibility. Stress and hormonal fluctuations, such as those occurring during menstruation, are also recognized triggers. Additionally, some toothpastes containing sodium lauryl sulfate (SLS) can contribute to their formation. Underlying medical conditions like celiac disease, inflammatory bowel disease, or a weakened immune system can also be associated with canker sores.
Management and When to Seek Professional Advice
Most canker sores are minor and typically heal on their own within one to two weeks. For pain relief and to promote healing, simple home remedies can be effective. Rinsing the mouth with warm salt water or a baking soda solution can help alleviate discomfort. Over-the-counter topical anesthetics containing ingredients like benzocaine or lidocaine, or protective pastes, can provide temporary pain relief. Avoiding trigger foods that are acidic, spicy, or abrasive, and practicing good oral hygiene with a soft-bristled toothbrush, can prevent further irritation.
While most canker sores resolve without medical intervention, it is important to know when to consult a healthcare professional. Seek advice if a canker sore is unusually large, persists for more than two to three weeks, or spreads. Extreme pain that interferes with eating or drinking, frequent recurrence, or accompanying symptoms like fever or systemic illness also warrant a medical evaluation.