• anaphylaxis;
  • cow’s milk proteins;
  • hen’s egg proteins;
  • food allergy;
  • hidden allergens;
  • probiotics.

To cite this article: Martín-Muñoz MF, Fortuni M, Caminoa M, Belver T, Quirce S, Caballero T. Anaphylactic reaction to probiotics. Cow’s milk and hen’s egg allergens in probiotic compounds. Pediatr Allergy Immunol 2012: 23: 778–784.


Background:  Probiotics are used in the treatment of allergic diseases. We investigated the safety of probiotics for subjects with food allergy.

Material and methods:  Labels of probiotics commercially available in Spain were examined to assess their content of cow’s milk or hen’s egg. Skin prick tests with these compounds (20 mg/ml) were performed in five children allergic to cow’s milk, five children allergic to hen’s white egg, and five control subjects non-allergic to food. Three serum pools: I (positive-specific IgE to cow’s milk and hen’s egg white proteins), II (positive-specific IgE to cow’s milk and negative to hen’s egg white proteins), and III (negative-specific IgE to cow’s milk and positive to hen’s egg white proteins) were used to detect cow’s milk and hen’s egg white allergens in probiotics. ImmunoCAP® (Phadia), in-house ELISA, SDS-PAGE immunoblotting, and inhibition studies of these assays were performed. Proteins were quantified by enzyme-immunoassay.

Results:  Eleven probiotics were studied. No label advertised about egg content, eight labels warned about lactose, lactic acid or cow’s milk, one label claimed to be milk-free, and two gave no information. Cow’s milk proteins were detected, by at least one lab technique, in 10/11 probiotics, three over 2.5 mg/kg (21, 52, 112 mg/kg). Hen’s egg white proteins were detected in 3/11 probiotics, only one had more than 2.5 mg/kg (47 mg/kg).

Conclusion:  Probiotic compounds may contain hidden allergens of food and may not be safe for subjects with allergy to cow’s milk or hen’s egg.