Allergies to certain types of food are very common among people of adult age group compared to children. Allergy is the result of certain proteins of the food being detected as harmful by our immune system. Allergy to citrus fruits such as grape fruits is very common among people. Symptoms of the allergy include itching and swelling of the mouth, lips, tongue, etc. Skin reactions as a result of the allergic reaction include eczema, itching, redness, swelling, etc. respiratory symptoms include stuffy nose, wheeze, sneezing, cough, difficulty to breathe. Cardiovascular symptoms include the decrease in blood pressure, fainting, etc.