Allergic Reactions

Diagnosis

To determine what is causing your symptoms, the doctor will conduct a medical history and do a physical examination. Allergic reactions are pretty obvious, as the symptoms usually come on shortly after exposure to the allergen. The physician treating you will check your blood pressure, pulse, and respiration, and ask you if you were exposed to any possible triggers (foods, medications, stings, etc.) prior to the reaction.

The doctor may refer you to an allergist for skin tests. Skin tests involve injecting tiny amounts of various allergens (insect venoms, drugs, etc.) into your skin and waiting to see if a skin reaction occurs. If you are allergic to any of them, a hivelike swelling should form within 20 minutes.

After you have received the emergency medical treatment necessary—a combination that could include epinephrine (adrenaline), an antihistamine or corticosteroids, or heart drugs to stop an abnormal heart rhythm—and are stable, your doctor may run diagnostic tests to determine what caused the reaction. The doctor may wish to check blood levels of antibodies to specific allergens with a test called the radioallergosorbent test (RAST). X-rays will be taken if you have breathing symptoms or chest pain.

If a food is the suspected culprit, you may be asked to take tests to isolate the specific cause. Diagnosing food allergies sometimes requires detective work. After a positive skin test, your allergist may have you consume the suspected trigger food disguised in something (such as applesauce) and wait for a reaction. Your allergist may also wish to have you follow an elimination diet. For this test, you begin by cutting out all possible allergenic foods. Then, you start adding them back, one at a time, to see if a reaction occurs. As the name suggests, this diagnostic tool works by process of elimination.

Prevention and Screening

Alert your doctor to any known drug allergies you have and read package inserts before taking any medication. Steer clear of any drug to which you have a known allergy. In addition, stay away from drugs that are related to your known allergen, as related medications could cause a reaction as well. For example, if you are allergic to aspirin, do not take NSAIDs (ibuprofen, ketoprofen, naproxen, etc.); if you are allergic to penicillin, let your doctor know so he or she will not prescribe penicillin-related medications, such as amoxicillin. Always read package inserts for warnings just in case.

Read food labels and look for ingredients that could trigger an allergic reaction. Take precautionary measures when preparing food and dining out. If you know you are allergic to shrimp, obviously you know to pass on the shrimp cocktail. However, be aware that shrimp may be hidden in salads, casseroles, and other dishes. Be sure to ask before you eat. Some people are so sensitive that the steam from shellfish being cooked can trigger a reaction. These people should avoid restaurants with open kitchens or hibachi-style cooking tables.

Peanut allergies can be very severe and can occur at the slightest exposure. There have been reports of allergic reactions occurring in children who ate sandwiches that were cut with the same knife used to make peanut butter and jelly sandwiches for other kids. Be sure the cafeteria workers at your child’s school know of any allergies your child may have. Be sure to inform the parents of your child’s friends as well, to cut the risk that harmful food is served to your child unknowingly. When grocery shopping, read food labels carefully, checking for ingredients that may trigger reactions. Eggs may show up in ingredient lists as albumin, binders, or emulsifiers. The ingredients casein, lactose, and whey are derived from milk. When dining out, let the waiter or waitress know you have a food allergy and ask about the ingredients in the dish you are considering.

If you are highly allergic to stings, you may want to consider a treatment known as allergen immunotherapy to desensitize yourself to the allergen. Latex desensitization is not available in the U.S. Food immunotherapy is not effective, and may be dangerous. For this therapy, a small amount of allergen is injected under the skin. The amount is too small to cause a reaction, but large enough to block or damp down any reaction that might occur with subsequent exposure to the allergen.