about allergic reactions
- What happens in the body during a food-allergic reaction? The immune system mistakenly believes that a harmless substance, in this case a food item, is harmful. In its attempt to protect the body, it creates specific IgE antibodies to that food. The next time the individual eats that food, the immune system releases massive amounts of chemicals and histamines in order to protect the body. These chemicals trigger a cascade of allergic symptoms that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system.
- What are the common symptoms of a reaction? Symptoms range from a tingling sensation in the mouth, swelling of the tongue and the throat, difficulty breathing, hives, vomiting, abdominal cramps, diarrhea, drop in blood pressure, loss of consciousness, to death. Symptoms typically appear within minutes to two hours after the person has eaten the food to which he or she is allergic.
- What is the best treatment for food allergy? Strict avoidance of the allergy-causing food is the only way to avoid a reaction. Reading ingredient labels for all foods is the key to maintaining control over the allergy. If a product doesn't have a label, allergic individuals should not eat that food. If a label contains unfamiliar terms, shoppers must call the manufacturer and ask for a definition or avoid eating that food.
- Is there a cure for food allergies? Currently, there are no medications that cure food allergies. Strict avoidance is the only way to prevent a reaction. Many children can outgrow food allergies, although peanuts, nuts, fish, and shellfish are often considered life-long allergies.
- Should I stop eating the food that I think I'm allergic to? Randomly taking food out of your diet can leave you with an unbalanced diet that can cause other health problems. Additionally, you may become frustrated because you reach a point where you believe that everything you eat is causing a reaction. Seek the help of a doctor or board certified allergist before making significant changes in your diet.
- What is the best treatment for a food allergy reaction? Epinephrine, also called adrenaline, is the medication of choice for controlling a reaction. It is available by prescription in two products: EpiPen® auto injector; and AnaGuard® or AnaKit®, a 2-dose needle and syringe. Check with a physician for individualized advice.
- What is the difference between food allergy and food intolerance? Many people think the terms food allergy and food intolerance mean the same thing; however, they do not. A food intolerance is an adverse food-induced reaction that does not involve the immune system. Lactose intolerance is one example of a food intolerance. A person with lactose intolerance lacks an enzyme that is needed to digest milk sugar. When the person eats milk products, symptoms such as gas, bloating, and abdominal pain may occur. A food allergy occurs when the immune system reacts to a certain food. The most common form of an immune system reaction occurs when the body creates immunoglobulin E (IgE) antibodies to the food. When these IgE antibodies react with the food, histamine and other chemicals (called mediators) cause hives, asthma, or other symptoms of an allergic reaction.
- What information should I provide my doctor? Keep a food diary, for 1 to 2 weeks, of everything you eat, what symptoms you experience, and how long after eating they occur. This information, combined with a physical examination and lab tests, will help the doctor determine what, if any, food is causing your symptoms.
- What is the difference between a prick skin test and a blood test or RAST test? The prick skin test or a blood test (such as the RAST (or radioallergosorbent test) are commonly used to begin to determine if an allergy exists:
- A prick skin test is usually cheaper and can be done in the doctor's office. The doctor places a drop of the substance being tested on the patients' forearm or back and pricks the skin with a needle, allowing a tiny amount to enter the skin. If the patient is allergic to the substance, a wheal (mosquito bite-like bump) will form at the site within about 15 minutes.
- A RAST requires a blood sample. The sample is sent to a medical laboratory where tests are done with specific foods to determine whether the patient has IgE antibodies to that food. The results are usually received within one week.
- Which test is better? Although both tests are reliable, there are instances where one is better than the other. Many doctors use a RAST for young children or patients who have eczema or other skin problems that would make if difficult to read the results of a prick skin test. The results of either test are combined with other information, such as a history of symptoms and a food challenge, to determine whether a food allergy exists.
Source: The Food Allergy Network
For more information visit the Anaphylaxis Canada website where you'll find useful resources for schools, camps, children and tips. You may also register with the Canadian Anaphylaxis Registry to receive relevant updates, and news items.
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