Allergic reactions to "chocolate" have been attributed to undeclared ingredients, including tree nut, peanut and cow milk. "Hidden allergens" such as insect parts have also been found to be present in chocolate. To date, I have not seen a case of true cocoa allergy. A PubMed search did not find any reports of specific allergy to chocolate or cocoa butter.
Jacqueline A. Pongracic, MD, FAAAAI