Soybean Allergy in Cow Milk-Tolerant Infants

Seven infants aged 2 to 6 months presented with vomiting, diarrhea, apathy, and shocklike state up to 2 hours after ingesting 100 to 200 mL of soy-based formula. The reasons for the administration of soy-based formula were atopic family history, atopic dermatitis, constipation, acute gastroenteritis, and Jewish dietary (Kashrut) laws; in only one patient was soybased formula given because of cow milk allergy. Three of the patients had a similar reaction on repeated inadvertent exposure to soy-based formula. Five infants tolerated humanized milk formula without any adverse events. In one infant an allergic reaction to humanized milk formula (generalized urticaria and vomiting) developed at age 8 months, up to which time he had been exclusively breast fed. Only one infant had a positive skin test to soybean. The two cow milk-allergic infants had a positive skin test to cow milk. Five infants underwent oral soybean challenges at age 12 to 24 months, all of which were negative. We conclude that soybean allerg...