Etiology of Riboflavin Deficiency Primary riboflavin deficiency results from inadequate intake of the following: Fortified cereals Milk Other animal products Secondary riboflavin deficiency is most commonly caused by the following: Chronic diarrhea Malabsorption syndromes Liver disorders Hemodialysis Peritoneal dialysis Long-term use of barbiturates Chronic alcohol use disorder Symptoms and Signs of Riboflavin Deficiency The most common signs of riboflavin deficiency are pallor and maceration of the mucosa at the angles of the mouth (angular stomatitis) and vermilion surfaces of the lips (cheilosis), eventually replaced by superficial linear fissures.