Cracked corners of the mouth, clinically more commonly known as stomatitis, are caused by a deficiency of vitamin B, mainly vitamin B2. Vitamin b2, also known as riboflavin, may be caused daily by a lack of animal protein in the diet, fresh vegetables, or eating overly refined rice and white flour. In addition a few patients with absorption disorders, such as severe chronic diarrhea, small intestine lesions can also lead to riboflavin malabsorption without cracking the corners of the mouth. Some patients with wasting diseases may also suffer from riboflavin deficiency due to accelerated metabolism of the body, resulting in cracked corners of the mouth.