[Loss of tolerance : Anaphylaxis after milk protein shake consumption in an adult sportsman].

We describe the case of a man who developed an acute allergic reaction for the first time in his life directly after drinking a protein shake after a workout session. Allergy diagnostics, including skin prick testing and the determination of specific IgE antibodies revealed sensitizations to cow's milk and hen's egg. Due to the association between the onset of symptoms after ingestion of a milk protein shake, a type-1-allergic reaction to milk protein was suggested. The patient denied a provocation test, although this could have been an opportunity to elucidate the role of physical exercise in this case. We suspect in the present case a loss of tolerance of early childhood sensitization due to repetitive high protein exposure in the context of physical activity. The patient was provided information regarding dietary and emergency management.