Aphthous stomatitis is not considered to be true aphthous stomatitis by some sources. Some of these conditions may cause ulceration on other mucosal surfaces in addition to the mouth such as the conjunctiva or the genital mucous membranes. Resolution of the systemic condition often leads to decreased frequency and severity of the oral ulceration. Behçet's disease is a triad of mouth ulcers, genital ulcers and anterior uveitis. The main feature of Behçet's disease is aphthous-like ulceration, but this is usually more severe than seen in aphthous stomatitis without a systemic cause, and typically resembles major or herpetiforme ulceration or both. Aphthous-like ulceration
Aphthous stomatitis unknown and are thought to be multiple and varied from one person to the next. This suggests that there are a number of possible triggers, each of which is capable of producing the disease in different subgroups. In other words, different subgroups appear to have different causes for the condition. These can be considered in three general groups, namely primary immuno-dysregulation, decrease of the mucosal barrier and states of heightened antigenic sensitivity (see below). Risk factors in aphthous stomatitis are also sometimes considered as either host-related or environmental. At least 40% of people with aphthous stomatitis have a positive family