Canker sores, scientifically known as aphthous ulcers, are small, painful lesions that develop on the soft tissues inside the mouth, such as the tongue, cheeks, or gums. These ulcers typically appear white or yellow with a distinct red border. While the exact cause remains uncertain, they usually heal on their own within one to two weeks.
Key Vitamin and Mineral Deficiencies
Deficiencies in specific micronutrients are among the most identifiable causes of recurrent canker sores, particularly those involved in cell division and mucosal health. The most commonly implicated are certain B vitamins and a few specific minerals required for tissue maintenance. These deficiencies can lead to atrophy, or thinning, of the protective mucosal lining inside the mouth, making it more susceptible to ulceration from minor trauma.
Vitamin B12 (cobalamin) is frequently associated with recurrent aphthous stomatitis because it is necessary for DNA synthesis and the formation of red blood cells. A lack of B12 can impair the rapid regeneration of cells needed to maintain the oral mucosa, increasing the likelihood of lesions. Folate (Vitamin B9) works closely with B12 in these cellular processes, and its deficiency similarly compromises the integrity of the mucosal barrier.
Iron deficiency is another well-established factor that can manifest with oral symptoms like recurrent ulcers. Iron is central to oxygen transport and enzyme function, and inadequate levels can hinder the healing process and the overall health of the oral tissues. Zinc deficiency is also a consideration, as this mineral plays a significant role in immune function and wound healing.
Environmental and Immune Triggers
Canker sores are often triggered by factors that irritate the oral lining or influence the body’s immune response. Physical trauma is a common trigger, where minor injuries create a site for an ulcer to form. This can result from accidentally biting the inside of the cheek, aggressive toothbrushing, abrasive dental work, or friction from orthodontic devices.
Emotional factors, such as high stress and anxiety, have also been linked to outbreaks. One theory suggests that stress may lead to subtle changes in the immune system, making the body more prone to a localized inflammatory response. Hormonal fluctuations are another recognized trigger, with some women reporting an increased incidence of canker sores during their menstrual cycle.
Certain food sensitivities and chemical irritants can also initiate an ulcer in susceptible individuals. Highly acidic foods, such as citrus fruits, pineapples, and tomatoes, can irritate the oral mucosa and trigger a lesion. Furthermore, some individuals react to ingredients found in oral hygiene products, such as sodium lauryl sulfate (SLS), a common foaming agent in toothpaste.
Treatment and Medical Consultation
For the majority of people, canker sores are minor and will resolve naturally, but symptom management can significantly reduce discomfort during the healing period. Over-the-counter topical treatments containing benzocaine or hydrogen peroxide rinses can be applied directly to the sore to provide temporary pain relief. Simple home remedies, such as rinsing the mouth with a solution of salt water or dissolving baking soda in warm water, can also help soothe the pain.
Avoiding known triggers is an important part of home care; this includes temporarily eliminating abrasive, spicy, or highly acidic foods from the diet. Switching to a toothpaste that does not contain the foaming agent sodium lauryl sulfate may also help reduce the frequency of recurrence. Maintaining consistent, gentle oral hygiene is necessary to prevent secondary bacterial infection of the open ulcer.
While most canker sores are benign, medical consultation is necessary if an ulcer persists for longer than two weeks, is unusually large, or recurs with debilitating frequency. A healthcare provider may order blood tests to investigate underlying systemic issues, particularly malabsorption conditions. Chronic or severe recurrent ulcers can sometimes be an oral manifestation of an underlying systemic disease, such as Crohn’s disease or Celiac disease, which require a formal diagnosis for proper management.