allergy An allergy refers to a misguided reaction by our immune system in response to bodily contact with certain foreign substances. It is misguided because these foreign substances are usually harmless and remain so to non- allergic people. Allergy-producing substances are called "allergens." Examples of allergens include pollens, dust mite, molds, danders, and foods. To understand the language of allergy it is important to remember that allergens are substances that are foreign to the body and can cause an allergic reaction in certain people. When an allergen comes in contact with the body, it causes the immune system to develop an allergic reaction in persons who are allergic to it. When you inappropriately react to allergens that are normally harmless to other people, you are having an allergic reaction and can be referred to as allergic or atopic. Therefore, people who are prone to allergies are said to be allergic or "atopic." Austrian pediatrician Clemens Pirquet (1874-1929) first used the term allergy. He referred to both immunity that was beneficial and to the harmful hypersensitivity as "allergy." The word allergy is derived from the Greek words "allos," meaning different or changed and "ergos," meaning work or action. Allergy roughly refers to an "altered reaction." The word allergy was first used in 1905 to describe the adverse reactions of children who were given repeated shots of horse serum to fight infection. The following year, the term allergy was proposed to explain this unexpected "changed reactivity." Allergy Fact · It is estimated that 50 million North Americans are affected by allergic conditions. · The cost of allergies in the United States is more than $10 billion dollars yearly. · Hay fever affects about 35 million Americans, 6 million of whom are children. · Asthma affects 15 million Americans, 5 million of whom are children. · The number of cases of asthma has doubled over the last 20 years. Allergy Symptoms

allergy (See also Food Allergy Symptoms) Allergy symptoms often involve sinuses and eyes: * A runny nose * Watery, itchy eyes * Sneezing * Allergic shiners - the dark circles children with allergies often get under their eyes * An allergic salute common in children - the upward tilt of the nose with a crease on top, caused by the child's continual upward swiping at an itchy nose. People with allergy symptoms often have asthma. Sometimes a cough is the first symptom of asthma, but a cough can be a symtpom of other things also. Wheezing, especially at night or after exercise, is common with asthma. Atopic skin diseases such as eczema, together with a runny nose and asthma, form what is known as an "allergic triad" of the three conditions most commonly associated with symptoms of allergies. A rash can be a symptom of contact dermatitis caused by an allergy to something that has come in contact with the skin, such as poison ivy or metal. Another skin condition, urticaria (hives), is often considered a symptom of allergies, but not all urticaria is caused by an allergic response. Allergic urticaria is often related to drug, food, or latex allergies, but many times it is not known what triggers the urticaria. Allergies cause increased drainage which can collect in the sinus cavities or ears. This moisture is a perfect environment for bacteria to grow, and many people with allergies have chronic sinus infections or ear infections. Gastro-intestinal symptoms such as burning in the mouth and throat, nausea, bloating, and diarrhea can sometimes occur with allergies to foods. Patients with allergies often complain of increased fatigue which improves when they get their allergy symptoms under control. Treatment The only way to avoid an allergic reaction is to avoid foods that cause signs and symptoms. However, despite your best efforts, you may come into contact with a food that causes a reaction. In this case, you may need an emergency injection of adrenaline (epinephrine) and a trip to the emergency room. In fact, if you have a severe allergy, you may need to carry injectable epinephrine with you at all times. For less severe allergies, your doctor may prescribe antihistamines, which can be taken after exposure to an allergen to control your reaction and help relieve discomfort. Creams may relieve skin reactions. Causes In a true food allergy, your immune system mistakenly identifies a specific food or component of food as a harmful substance. Your immune system triggers certain cells to produce immunoglobulin E (IgE) antibodies to fight the culprit food or food component (the allergen). The next time you eat even the smallest amount of that food, the IgE antibodies sense it and signal your immune system to release histamine and other chemicals into your bloodstream. These chemicals cause a range of allergic signs and symptoms. Histamine is partly responsible for most allergic responses, including dripping nose, itchy eyes, dry throat, rashes and hives, nausea, diarrhea, labored breathing and even anaphylactic shock.

allergy The great majority of food allergies are triggered by certain proteins in: * Eggs * Peanuts * Fish * Shellfish, such as shrimp, lobster and crab * Tree nuts, such as walnuts and pecans In children, food allergies are also commonly triggered by proteins in these foods: * Cow's milk * Wheat * Soybeans Chocolate, long thought by some parents to be a culprit among children, seldom is a cause of allergy. Food intolerances and other conditions: Not food allergies Other reactions to food don't involve your immune system or, consequently, the release of histamine. These reactions aren't true food allergies. Instead, they may be food intolerances. Because food intolerances may involve many of the same signs and symptoms as food allergies do — such as nausea, vomiting, cramping and diarrhea — people often confuse the two. If you have a food intolerance, you usually can eat small amounts of problem foods without a reaction. By contrast, if you have a true food allergy, even a tiny amount of food may trigger an allergic reaction. One of the tricky aspects of diagnosing food intolerance is that some people are sensitive not to the food itself but to a substance or ingredient used in the preparation of the food. For example, sulfite preservatives can trigger asthma in sensitive people. Common causes of food-related problems include: * Absence of an enzyme needed to fully digest a food. You may not have adequate amounts of some enzymes needed to digest certain foods. Insufficient quantities of the enzyme lactase, for example, make it difficult to digest lactose, the main sugar in milk products. Lactose intolerance can cause bloating, cramping, diarrhea and excess gas. * Irritable bowel syndrome. Certain foods may trigger the signs and symptoms of irritable bowel syndrome. You may find that certain foods will cause cramping, constipation or diarrhea. You may avoid these foods to avoid the symptoms. * Food contaminated by a toxin. Sometimes food poisoning can mimic an allergic reaction. Some types of mushrooms and rhubarb, for example, can be toxic. Bacteria in spoiled tuna and other fish also can make a toxin that triggers adverse reactions. * Recurring stress or psychological factors. Sometimes the mere thought that a food may make you sick actually does. The reason is not fully understood.