Canker sores, medically known as aphthous ulcers, are small, painful lesions that appear on the soft tissues inside the mouth, such as the inner cheeks, lips, and tongue. They typically present as a round or oval ulcer with a white or yellowish-gray center surrounded by a red border. Unlike cold sores, these ulcers are not contagious and are not caused by the herpes virus, but they make eating and speaking extremely uncomfortable. The belief that one should attempt to “dry out” a canker sore is counterproductive, often increasing pain and irritation and potentially delaying healing.
The Practice of Drying Out Canker Sores
The instinct to “dry out” a canker sore arises from the common experience of treating a skin wound, where drying can lead to a protective scab that speeds healing. People often attempt this by applying harsh agents directly to the sore, such as dry table salt, undiluted hydrogen peroxide, or astringents. This method is based on a misunderstanding of the oral environment, where ulcers form on moist mucosal tissue, which is structurally different from skin.
When a harsh substance is applied, it rapidly draws water out of the cells, a process called cellular dehydration. This causes immediate, intense pain and localized tissue damage, known as necrosis, which is the perceived “drying” effect. While this may temporarily cauterize nerve endings for brief pain relief, the resulting tissue injury and severe irritation can prolong the overall healing period. The mouth’s constant moisture prevents the formation of a stable, protective scab, meaning the irritation keeps the ulcer an open, inflamed wound.
Understanding Canker Sore Causes
The precise reason canker sores develop is not fully clear, but outbreaks are frequently linked to several triggers. Physical trauma is a common factor, often caused by accidentally biting the cheek, aggressive toothbrushing, or irritation from sharp dental work.
Nutritional deficiencies, particularly low levels of Vitamin B12, folate, iron, or zinc, can increase susceptibility. Acidic or spicy foods, like citrus fruits, tomatoes, or vinegar, are known to either trigger a sore or worsen an existing one. Emotional stress is also a trigger, with episodes often coinciding with periods of high anxiety. Furthermore, some individuals react to the detergent sodium lauryl sulfate (SLS), a common foaming agent found in many toothpastes and mouth rinses.
Recommended Treatment Strategies
The goal of effective treatment is to protect the open wound, manage discomfort, and facilitate the body’s natural healing process. Pain can be managed immediately through topical anesthetics, such as gels or liquids containing benzocaine or lidocaine, which temporarily numb the area. Over-the-counter pain relievers also help reduce inflammation and aching associated with the ulcer.
Protective barrier films or pastes are effective because they shield the nerve endings from contact with food, drink, and saliva, reducing mechanical irritation. Gentle, non-irritating oral rinses are recommended to keep the area clean and reduce the bacterial load. A simple saline solution or a diluted rinse of half water and half 3% hydrogen peroxide can be used to cleanse the area. For severe or persistent sores, a medical professional may prescribe topical corticosteroids, such as dexamethasone, to reduce inflammation.
Minimizing Future Outbreaks
Long-term management focuses on identifying and avoiding individual triggers to reduce the frequency of recurrence. Limiting or eliminating known irritants like highly acidic or spicy foods is a primary step. Ensuring a balanced intake of vitamins and minerals is also important, and supplements may be recommended if a deficiency in B vitamins, iron, or zinc is suspected.
Maintaining gentle oral hygiene is crucial, which includes using a soft-bristled toothbrush to prevent micro-trauma to the mouth lining. Switching to toothpastes that do not contain sodium lauryl sulfate (SLS) can prevent chemical irritation for those sensitive to the detergent. Finally, incorporating stress-reduction techniques, such as meditation or regular exercise, can help manage the systemic factors that often precede an outbreak.