It could be due to iron deficiency anemia, pernicious anemia and other B-vitamin deficiencies, aphthous ulcers, oral lichen planus, erythema multiform, pemphigus vulgaris, syphilis,
yeast infection; exposure to irritants such as hot foods, or spices, tobacco, alcohol; allergy to toothpaste, mouthwash, breath fresheners, dyes in candy, dentures, food items, coloring agents, or blood pressure medications like ACE inhibitors.