Aphthous stomatitis countries. Within nations, it is more common in higher socioeconomic groups. Males and females are affected in an equal ratio, and the peak age of onset between 10 and 19 years. About 80% of people with aphthous stomatitis first developed the condition before the age of 30. There have been reports of ethnic variation. For example, in the United States, aphthous stomatitis may be three times more common in white-skinned people than black-skinned people. "Aphthous affectations" and "aphthous ulcerations" of the mouth are mentioned several times in the treatise "Of the Epidemics" (part of the Hippocratic corpus, in the 4th
Aphthous stomatitis and aphthous stomatitis is probably related to nutritional deficiencies caused by malabsorption. Less than 5% of people with RAS have Celiac disease, which usually presents with severe malnutrition, anemia, abdominal pain, diarrhea and glossitis (inflammation of the tongue). Sometimes aphthous-like ulcerations can be the only sign of celiac disease. Despite this association, a gluten-free diet does not usually improve the oral ulceration. Other examples of systemic conditions associated with aphthous-like ulceration include reactive arthritis, and recurrent erythema multiforme. Diagnosis is mostly based on the clinical appearance and the medical history. The most important diagnostic feature is a history of recurrent,