A canker sore, medically known as an aphthous ulcer, is a common type of mouth sore that develops on the soft tissues inside the mouth. These small, shallow lesions typically appear as white or yellowish open wounds with a distinct red border. Canker sores can form on various internal surfaces, including the inside of the lips, cheeks, on or under the tongue, the gums, or the soft palate. Although they can be painful and make eating or talking uncomfortable, canker sores are not contagious and cannot be spread from person to person.
Understanding Canker Sore Formation
The exact process leading to canker sore development is not fully understood, but researchers believe a combination of factors contributes to their appearance. Minor injuries to the mouth lining often precede canker sores. This can result from accidental cheek or lip biting, aggressive toothbrushing, or irritation from dental work or orthodontic appliances.
Certain foods can also act as triggers, particularly those that are acidic, spicy, or abrasive. Examples include citrus fruits, tomatoes, strawberries, chocolate, and nuts, which may irritate the oral tissues and lead to sore formation.
Nutritional deficiencies have been linked to an increased susceptibility to canker sores. Inadequate levels of certain vitamins and minerals, such as iron, folate, zinc, and vitamin B12, can play a role. These nutrients are involved in cell growth and repair, and their deficiency may compromise oral mucosa integrity.
Emotional and psychological stress is another recognized factor associated with canker sore outbreaks. Stress may weaken the immune system or lead to habits like lip biting, increasing vulnerability. Some individuals report sores appearing several days after a stressful event.
Hormonal fluctuations, particularly in women, can influence the occurrence of canker sores. Many women experience outbreaks during specific phases of their menstrual cycle, with changes in hormones like progesterone potentially contributing to oral tissue changes.
Both a weakened or overly reactive immune response can be implicated. An immune system unable to quickly repair tissue damage may contribute to canker sore formation. Some researchers also suggest an allergic response to certain mouth bacteria.
Some common ingredients in oral care products, such as sodium lauryl sulfate (SLS) found in many toothpastes, have been associated with increased canker sore frequency. Food sensitivities, beyond just acidic or abrasive foods, and genetic predisposition also contribute, as a family history of canker sores increases the likelihood of developing them.
Canker Sore vs. Cold Sore: Key Differences
Distinguishing between a canker sore and a cold sore is important due to their different origins and characteristics. Their typical location is a key differentiator. Canker sores exclusively form inside the mouth, appearing on soft tissues like the inner cheeks, lips, tongue, or gums. In contrast, cold sores, also known as fever blisters, usually develop outside the mouth, most commonly on or around the lips, though they can sometimes appear on the nose, chin, or other facial areas.
Appearance also differs significantly. Canker sores present as small, shallow ulcers with a white or yellowish center and a distinct red border. They can be singular or appear in small clusters. Cold sores, however, typically begin as fluid-filled blisters that often cluster together. These blisters eventually break open, ooze, and then crust over before healing.
The underlying cause is another primary distinction. Canker sores are not caused by an infection; their development is multifactorial, involving various triggers and individual predispositions. Cold sores, conversely, are caused by the highly contagious herpes simplex virus (HSV), most often HSV-1. Once infected, the virus remains dormant in the body and can reactivate periodically, leading to outbreaks.
This viral origin makes cold sores highly contagious, spreading through close personal contact like kissing or sharing utensils, even when no blisters are visible.