Eosinophilic (allergic) proctocolitis is one of the most common causes of rectal bleeding in infants and usually presents in children less than 2 months. This colitis is felt to be caused by the ingestion of immunogenic food proteins in infant formula or through the mother’s breast milk. The more common inciting food proteins include cow’s milk (7.5% of the population) and soy (0.5% of the population). Children who are sensitive to cow’s milk protein are also often sensitive to soy protein.
