The precise cause of canker sores is unknown. Nonetheless, canker sores seem to pop up in the course of certain diseases almost as a symptom of that disease. These “canker sore diseases” range from viral and bacterial infections to gastrointestinal disorders to nutritional deficits. Moreover, food allergies are sometimes associated with canker sores meaning that certain foods may trigger canker sore eruptions in some people. Other conditions that are not necessarily diseases have also been linked to aphthous ulcers such as hormonal changes and poor oral hygiene.

Viral and bacterial infections

One common question that patients have about canker sores is: “are canker sores contagious?” This is an important question because so many mouth sores are contagious and sufferers do not want close and intimate contacts exposed to a contagious oral disease. Fortunately, canker sores are not contagious even though many laypeople seem to worry that they are. One reason that people erroneously think that canker sores are contagious is that they seem to occur during and just after other infections. Viruses and bacteria that may make sufferers more susceptible are:

• Cytomegalovirus (CMV)
• Epstein-Barr virus (EBV)
• Helicobacter species (bacteria)
• Herpes simplex viruses 1 and 2
• Human herpesvirus
• Human papilloma virus (HPV),
• Streptococci (bacterial)
• Varicella zoster virus

While aphthous ulcers may occur when people are affected by one of these infectious diseases, none of them are specifically responsible for cankers sores.

Gastrointestinal disorders

Crohn’s disease and ulcerative colitis are separate gastrointestinal diseases collectively known as inflammatory bowel disease. These inflammatory bowel diseases are characterized by lesions in the wall of the digestive tract. Crohn’s disease can affect any part of the gastrointestinal tract, from mouth to anus. Ulcerative colitis, on the other hand, affects the large intestine (colon) exclusively. Patients suffering from either inflammatory bowel disease are known to have increased rates of canker sores. In fact, as many as one in five people with inflammatory bowel disease have recurrent canker sores.

Canker sore treatment: canker sore home remedy

Celiac disease is a gastrointestinal disorder in which sufferers cannot properly digest gluten, a protein found in wheat, barley, and rye. Many people that are intolerant to gluten are also afflicted with canker sores. In fact, limited evidence suggests that gluten exposure may trigger an aphthous ulcer in some people.

Nutritional deficits

One of the classic “causes” of canker sores is a deficiency in Vitamin B₁₂. In truth abnormally low levels of a wide variety of vitamins have been connected to canker sores. Deficiencies in the following vitamins can lead to aphthous ulcers.

• Folic acid (aka folate)
• Iron
• Vitamin B₁
• Vitamin B₂
• Vitamin B₆
• Vitamin B₁₂
• Vitamin C
• Zinc

Fortunately if a deficiency in one of these vitamins is identified as the probable cause of a canker sore, the treatment is straightforward: simply supplement the vitamin. In fact, Vitamin B₁₂ may be a canker sore treatment in even those who do not have a clinical deficiency.

Diseases that affect the immune system

Any illness that significantly depresses the immune system may create an opportunity for aphthous ulcers to form. It is well known that patients infected with HIV, more specifically those with AIDS, struggle with fairly severe canker sores. Moreover, patients with decreased levels of circulating white blood cells (a condition known as neutropenia) often also have canker sores. Canker sores also come about in certain immune diseases like Behçet’s disease, for instance. Behçet’s disease is characterized by a chronic inflammation of the blood vessels.

References

Jose FA, Garnett EA, Vittinghoff E et al. Development of extraintestinal manifestations in pediatric patients with inflammatory bowel disease. Inflamm Bowel Dis 2009;15:63-68.

Trost LB, McDonnell JK. Important cutaneous manifestations of inflammatory bowel disease. Postgrad Med J 2005;81:580-585.

Besu I, Jankovic L, Magdu IU, Konic-Ristic A, Raskovic S, Juranic Z. Humoral immunity to cow’s milk proteins and gliadin within the etiology of recurrent aphthous ulcers? Oral Dis 2009;15:560-564.

Volkov I, Rudoy I, Freud T et al. Effectiveness of vitamin B12 in treating recurrent aphthous stomatitis: a randomized, double-blind, placebo-controlled trial. J Am Board Fam Med 2009;22:9-16.