“Idiopathic” anaphylaxis caused by carboxymethylcellulose in ice cream

Foods, medications, and hymenoptera venom are recognized elicitors of anaphylaxis.1 However, up to 59% of cases have been labeled "idiopathic anaphylaxis."2 In those patients, mastocytosis, cofactor-induced anaphylaxis, or hidden allergens may play a role.3,4 Carboxymethylcellulose (CMC) is a hydrophilic additive commonly used to bind, stabilize, and thicken substances in food and pharmaceutical products. Several cases of anaphylaxis caused by CMC contained in drugs have been reported,5-7 but CMC now also has to be considered an elicitor of anaphylaxis in food products.