Systemic reaction to an extensively hydrolyzed formula in an infant with cow's milk anaphylaxis

Cow's milk allergy is the most common cause of food allergy in young children. Ingestion of milk products in children with a milk protein allergy can lead to anaphylaxis and must be avoided. Some guidelines suggest the use of an extensively hydrolyzed formula (EHF) in these cases; however, rare allergic reactions can still occur. Here, we presented a 3-month-old boy who developed anaphylaxis to a cow's milk formula. Subsequently, he developed a rare systemic reaction to soy and to an EHF.

The patient had an unremarkable medical history and presented with signs and symptoms consistent with anaphylaxis after being fed cow's milk formula for the first time. Symptoms included immediate vomiting, wheezing, stridor, angioedema of eyelids and lips. Although intramuscular epinephrine was given, the patient continued to clinically deteriorate, becoming more lethargic and necessitating admission to the pediatric intensive care unit. Subsequently, a trial of soy formula ingestion reproduced the symptoms and an EHF was given. However, immediately after taking an EHF, he developed facial angioedema and diffuse urticarial lesions.

In most patients with a cow's milk allergy, an extensively based formula can be tolerated safely due to a hydrolyzed protein chain. However, medical providers must be vigilant when switching formula because a rare systemic allergic reaction to EHF can still occur.