Allergies to cacao (the bean that is the main ingredient in chocolate) are possible but so rare as to be virtually nonexistent in recent medical literature. Therefore, if you've experienced food allergy symptoms after eating chocolate, you can safely assume that another ingredient in the chocolate is causing your symptoms unless testing shows otherwise. (If you do experience allergy symptoms, call your doctor as soon as possible to discuss testing. Symptoms of anaphylaxis represent an emergency; take epinephrine immediately, if available, and call for an ambulance.)
One reason so many people experience allergy and food intolerance symptoms after eating chocolate is that chocolates often contain foods that are problematic for people. Here are some allergens, additives, and drug interactions to be aware of with chocolate (note: always double-check where brand names are listed, as some may change manufacturing practices without warning):
- Milk. Dairy allergies are very common, especially in children, and almost all chocolate contains at least some milk. If you're lactose intolerant and can tolerate small amounts of dairy products, try bittersweet, semisweet, or dark chocolate: It's required by law to contain a higher percentage of chocolate liquor and, therefore, has less milk and sugar. Dairy-free chocolates are on the market from brands like Tropical Source, Amanda's Own, and Chocolate Decadence.
- Peanuts and Tree Nuts. Obviously, some chocolates are filled with peanut butter or with whole nuts. But even chocolates that don't include peanuts or tree nuts as ingredients can be problematic for people with peanut allergies or tree nut allergies because manufacturers that make chocolate assortments containing nuts often make all of their chocolates on the same manufacturing line. FALCPA regulations do not require manufacturers to mention this on food labels, so always call manufacturers before eating high-risk foods like chocolates. You can also buy chocolate from nut-free manufacturers like Vermont Nut-Free, Nothin' Nutty, or The Chocolate Truffle, or look for label indications like "manufactured in a dedicated nut-free facility."
- Wheat and Gluten. The same issues that apply to peanuts and tree nuts also affect people with wheat allergies and celiac disease. Filled chocolates often use flour or wheat starch as a binder, and crisped rice can be problematic for celiacs because it often includes barley malt. Gluten-free chocolatiers include Endangered Species Chocolate and Equal Exchange.
- Soy. Technically, chocolate is an emulsion (a mixture of two liquids that would otherwise separate), and just like mayonnaise and shelf-stable salad dressings, it usually includes an emulsifier to keep it solid at room temperature. Among the most common is soy lecithin, which is problematic for many people with soy allergies. This should be listed clearly on food labels.
- Corn. Corn is incredibly difficult to avoid in the industrial food supply, and chocolate is no exception. In addition to high fructose corn syrup in some chocolate brands, some manufacturers may use corn on production lines. Be especially alert for the presence of corn in white chocolate.
- Berries. Berries are among the more common allergenic fruits. Be careful of assortments; no matter how carefully you read the legend indicating which type of chocolate is located where in the box, it's too easy for pieces to get mixed up.
- Caffeine. Contrary to popular belief, chocolate is extremely low in caffeine: one ounce of milk chocolate contains only six milligrams of caffeine. In comparison, one 12-ounce can of Coca-Cola has 34 milligrams, and a 2-ounce double espresso can range from 45 to 100 milligrams. However, if you are highly sensitive to caffeine, chocolate may exacerbate your symptoms, and you may find that you're better off avoiding it. Dark chocolate has far more caffeine than milk chocolate.
- Drug Interactions. Rarely, chocolate may cause symptoms that resemble allergy symptoms (like itchiness, or pruritus) in people taking the common psychiatric medication Prozac (flouxetine). It's possible that the sensitivity to the biological chemical serotonin that seems to cause this uncommon reaction could occur in the presence of other selective serotonin reuptake inhibitors, or SSRI drugs. Be sure your allergist is aware of any medications you're taking before you undergo allergy testing; this could be especially useful information if your tests are negative.
Cederberg, Jonas, et al. "Itch and Skin Rash from Chocolate During Fluoxetine and Sertraline Treatment: Case Report." BMC Psychiatry. 2004. 4:36.