# Frey’s syndrome in an infant misdiagnosed as food allergy

## TL;DR

An infant was misdiagnosed with food allergies but actually had Frey’s syndrome, a condition causing facial flushing and sweating during feeding.

## Contribution

Highlights Frey’s syndrome as a misdiagnosed mimic of food allergy in infants, emphasizing the need for allergist awareness.

## Key findings

- The infant showed unilateral facial flushing and sweating during feeding, not urticaria or systemic allergy symptoms.
- Skin prick and IgE tests for food allergens were negative, confirming the absence of IgE-mediated allergy.
- A supervised food challenge and home video confirmed Frey’s syndrome, not food allergy.

## Abstract

Frey’s syndrome (auriculotemporal syndrome) is characterized by gustatory flushing and sweating in the distribution of the auriculotemporal nerve. Although classically described after parotid surgery in adults, congenital and idiopathic forms are increasingly recognized in infants. Because symptoms occur during feeding, the condition can closely mimic IgE-mediated food allergy, leading to unnecessary dietary restrictions and anxiety.

We report an 8-month-old boy referred for evaluation of suspected multiple food allergies after several emergency department visits for feeding-associated facial redness, interpreted by caregivers as “hives”, and accompanied by significant parental anxiety and progressive dietary avoidance. On detailed reassessment, reactions were found to consist of localized, unilateral flushing and sweating of the right cheek, without urticaria or systemic features. Skin prick testing and serum-specific IgE testing to common food allergens were negative. During a supervised baked milk oral food challenge, a similar unilateral cutaneous reaction was observed, confirming the diagnosis of Frey’s syndrome. A home-recorded video demonstrated comparable findings during feeding with formula.

Frey’s syndrome is an important and under-recognized mimic of food allergy in infancy. Careful attention to laterality, absence of systemic involvement, and reproducibility across foods can prevent misdiagnosis, reduce unnecessary dietary restriction, and alleviate family anxiety.

Frey’s syndrome should be considered in infants with reproducible unilateral flushing during feeding. Awareness among allergists can prevent misdiagnosis, reduce unnecessary food avoidance, and support safe nutritional and developmental outcomes.