What causes a chocolate allergy?

Bad Luck!: Food allergies occur when the body's immune system recognizes a substance as being "foreign" to the body and potentially harmful. It then "attacks" this foreign invader, trying to eliminate it. This is helpful when the invader is a germ, but unfortunate when it is something as delightful as chocolate.

Never seen one: Chocolate has milk, sugar and cocoa. Cocoa allergy is very rare, I have never seen one. If you are allergic to milk, you will be allergic to all milk products. True immunologic reaction to food would occur in the form of hives and sometimes severe what we call anaphylactic reaction.

Workup/Mgt: Chocolate is a complex food, with potentially many additives such as fruits, nuts, flavorings. Determining which of the contents is causing a specific reaction is part of the workup and testing. Further management includes avoidance of the trigger. I would suggest discussing your symptoms and further workup with your physician. In the meantime, check ingredients and please avoid chocolate.

Uncommon: A person can become allergic to any food and at any age. Part of it is from genetic and also people with eczema are more likely to become allergic to food through skin contact. Avoidance if the best approach since this is not an essential nutrient.