Biphasic reactions in children undergoing oral food challenges

Literature regarding biphasic reactions in the pediatric population is sparse. We aimed to determine the prevalence of biphasic reactions in children with food allergies undergoing oral food challenges (OFCs) and examine whether any clinical or treatment factors are associated with biphasic reactions. A retrospective chart review of OFCs conducted between July 2007 and March 2011 was performed. Charts were reviewed from time of challenge to 48 hours after challenge to capture data on any biphasic reactions. Uniphasic and biphasic reactions were compared in terms of specific clinical features and treatments. Of 614 positive challenges, 9 resulted in a biphasic reaction (1.5%). Six of the biphasic reactions occurred in challenges where the initial reaction met anaphylaxis criteria. The biphasic reactions were to eggs (4), peanuts (3), and milk (2). The symptom-free interval ranged from 2 to 24 hours. There were no statistically significant differences in clinical features between uniphasic and biphasic reactions, but there appeared to be a higher percentage of initial reactions with multiple organ involvement and meeting anaphylaxis criteria in the biphasic group. Biphasic reactors were significantly more likely to have received steroids for their initial reaction. A higher percentage of biphasic reactors also appeared to have received epinephrine, multiple doses of epinephrine, and antihistamines for their initial reactions. Biphasic reactions are rare in children undergoing OFCs and may be associated with more severe allergic reactions. Children with severe reactions may benefit from a 24-hour period of observation.