Aphthous Stomatitis
Antigenic sensitivity

Various antigenic triggers have been implicated as a trigger, including some streptococci, herpes simplex virus, varicella-zoster virus, adenovirus, and cytomegalovirus.

Herpes virus, and antibodies (graphic)

Some people with aphthous stomatitis may show herpes virus within the epithelium of the mucosa, but without any productive infection.

Allergens

In some instances, recurrent mouth ulcers may be a manifestation of an allergic reaction. Possible allergens include certain foods (e.g., chocolate, coffee, strawberries, eggs, nuts, tomatoes, cheese, citrus fruits, benzoates, cinnamaldehyde, and highly acidic foods), toothpastes, and mouthwashes. Where dietary allergens are responsible, mouth ulcers usually develop within about 12–24 hours of exposure.

Sodium lauryl sulphate (SLS), a detergent present in some brands of toothpaste and other oral healthcare products, may produce oral ulceration in some individuals. It has been shown that aphthous stomatitis is more common in people using toothpastes containing SLS, and that some reduction in ulceration occurs when a SLS-free toothpaste is used.

There is also an argument that since SLS is almost ubiquitously used in oral hygiene products, there is unlikely to be a true predisposition for aphthous stomatitis caused by SLS.