It may sound scary that a cup of cappuccino can kill you. But the truth is, about two in every 50 people, especially teenagers, suffer from different kinds of food allergies that can lead to rashes, severe discomfort and, in the most severe cases, death. Potential 'killers' can include anything from your favourite seafood snack or innocent salad dressing, to the humble peanut - if your body is wired to reject these foodstuffs. According to Adrian Wu Young-yuen, University of Hong Kong's assistant professor of medicine and allergy specialist, a food allergy is an immune system response to a food that the body wrongly identifies as harmful and creates specific antibodies to repel. If you eat food to which you are allergic, your system releases massive amounts of chemicals that usually result in severe physical discomfort. Symptoms include abdominal cramps, asthma and other breathing difficulties, diarrhoea, hives, swelling of the throat and vomiting. But Dr Wu said it could sometimes be hard for young patients to distinguish whether the discomfort is related to an allergic reaction. 'To find out what's going on inside your body, the best thing is to visit an allergy and immunology specialist who can test your reactions against various foodstuffs, advise on an elimination diet, and teach allergy sufferers how to spot potentially dangerous materials in food labels,' he said. Dr Wu said it was impossible to compile a complete list of foods likely to cause discomfort. However, there are about eight common types of potentially dangerous food materials that can be hiding in some of your favourite dishes or snacks: 1. Toasted bread It's the butter on the bread that matters the most. Butter contains milk proteins which can trigger reactions. This is the breakfast for many school children, but the butter usually melts and disappear into nowhere. The Food Allergy and Anaphylaxis Network in the United States also advises allergy sufferers to take special caution when consuming steaks grilled with butter to add extra flavour. 2. Coffee Cappuccino can be a drink that gives you a kick on a boring afternoon. But eggs have been used to create the foam or milk topping. Beware that products like noodles and spaghetti also contain eggs, a common allergy-causing food. 3. Sichuanese Spicy Noodles (Dan Dan Mien) While the mouthwatering dish originates from Sichuan, it is also common in a lot of Shanghanese restaurants. Some people are allergic to noodles, but more hazardous are the peanut pieces sprinkled in the soup base. Just half a peanut can lead to severe allergic reactions in some people. 4. Japanese cold noodles (Chasoba Soba) You probably are aware that these cold noodles are made from wheat flour, another 'dangerous' food material. But wheat flour is quite commonly used in other foodstuffs, including vegetarian beef, pork and shrimp. 5. Curry chicken This is one of the most popular dishes in student canteens, but unfortunately it has coconut milk and sometimes peanuts. Coconut is a less common source of allergy, but some people do suffer reactions from it. 6. Caesar salad The salad dressing in this dish contains anchovies, which may provoke reactions in seafood-allergic individuals. In general, these people should also avoid going to fish and seafood restaurants, because of the risk of contamination in food preparation. Some people even experience allergic reactions from walking through a fish market. 7. Beancurd Your mother might keep on telling you that beancurd is good for your health. But soybean is not healthy at all for some people. If you are allergic to soy beans, you have to take extra caution when consuming canned tuna, crackers and soups. 8. Chocolate and nuts Chocolates can be delicious. However they usually contain peanuts or tree nuts like walnuts or cashews. People allergic to nuts should also be wary of labels which say the chocolate bar has artificial nuts - these can be peanuts that have been deflavoured and, believe it or not, reflavoured with artificial nut flavouring. But the allergy danger remains.