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 and keratinization. This subgroup often experiences remission during pregnancy. However, other studies report no correlation between aphthous stomatitis and menstrual period, pregnancy or menopause. Aphthous stomatitis is uncommon in people who smoke, and there is also a correlation between habit duration and severity of the condition. Tobacco use is associated with an increase in keratinization of the oral mucosa. In extreme forms, this may manifest as leukoplakia or stomatitis nicotina (smoker's keratosis). This increased keratinization may mechanically reinforce the mucosa and reduce the tendency of ulcers to form after minor trauma, or present a more substantial barrier to microbes and