Canker sores (aphthous ulcers) are a frequent oral affliction causing pain and discomfort. These small, shallow ulcers have a distinctive appearance: a white or yellowish center surrounded by a bright red border. They form exclusively on the soft tissues inside the mouth, such as the inner cheeks, lips, tongue, or at the base of the gums. While generally not serious, they can interfere with speaking and eating until they heal naturally, usually within one to two weeks.
Are Canker Sores Contagious?
Canker sores are not contagious and cannot be transmitted from person to person through contact. Unlike infections caused by viruses or bacteria, these ulcers are internal mucosal lesions (aphthous ulcers). They are not spread through kissing, sharing eating utensils, or drinking from the same cup.
The sores are a localized reaction within the mouth’s lining, not the result of a spreading pathogen. This means there is no need to isolate oneself or take special precautions to prevent transmission. Their development is linked to individual factors rather than an external infection.
Identifying Common Triggers
Since canker sores are not contagious, their appearance is linked to internal or environmental factors that can trigger an outbreak. A common cause is minor physical injury to the mouth’s lining, which can occur from accidental cheek biting, aggressive toothbrushing, or irritation from dental appliances like braces. These small breaks in the tissue can initiate ulcer formation.
Emotional stress is another frequently cited trigger, as it may affect the body’s normal immune function. Sensitivities to certain foods or ingredients can also contribute, including highly acidic items like citrus fruits and tomatoes. Some people find that toothpastes containing the foaming agent Sodium Lauryl Sulfate (SLS) can trigger or worsen canker sores.
Nutritional deficiencies, specifically low levels of Vitamin B12, iron, or folate, have been associated with recurring canker sores. Addressing these dietary gaps can help reduce the frequency of outbreaks. Recognizing and avoiding personal triggers is the most effective approach to prevention.
Canker Sores Versus Cold Sores
The distinction between canker sores and cold sores is important because they have different causes and treatments. The most apparent difference is their location: canker sores appear exclusively inside the mouth on soft tissues. Cold sores (fever blisters) form on the outside of the mouth, typically on the lips or around the nose.
Their cause is fundamentally different: canker sores are not infectious, while cold sores are caused by the highly contagious Herpes Simplex Virus (HSV). This viral cause makes cold sores easily transmissible through close physical contact or sharing items.
Canker sores present as a single, open ulcer with a defined white or yellow center and a red edge. In contrast, cold sores initially appear as clusters of small, fluid-filled blisters that eventually break open, ooze, and form a crust. These differences help in correctly identifying the condition.
Relief and Management Options
While most canker sores heal naturally within a couple of weeks, several options can help manage the associated pain and promote faster recovery. Over-the-counter topical anesthetics, such as gels or creams containing benzocaine or lidocaine, can be applied directly to the sore for temporary pain relief by temporarily numbing the exposed nerve endings.
Simple home remedies can also provide soothing relief, including rinsing the mouth with a solution of salt water or dissolved baking soda in warm water. This process helps clean the area and alleviate discomfort. Avoiding foods that may irritate the sore, such as spicy, acidic, or abrasive items, is recommended to prevent further pain.
In cases of large, persistent, or frequent sores that do not improve after two weeks, a healthcare provider should be consulted. A doctor may prescribe specialized mouth rinses, such as those containing a steroid like dexamethasone, to reduce inflammation and pain. For documented nutritional deficiencies, supplements like Vitamin B12 or iron may be recommended to manage recurrent outbreaks.