Allergies & the Immune System

What is skin testing for allergies?
– Julia

The most common way to test for allergies is on the skin, usually the forearm or the back. In a typical skin test (also called a scratch test), a doctor or nurse will place a tiny bit of an allergen (such as pollen or food) on the skin, then prick the outer layer of skin or make a small scratch on the skin.

The allergist may repeat this, testing for several allergens in one visit. This can be a little uncomfortable, but not painful.

If a child reacts to one of the allergens, the skin will swell a little in that area. The doctor will be able to see if a reaction happens within about 15 minutes. The swelling usually goes down within about 30 minutes to a few hours. Other types of skin testing include injecting allergens into the skin or taping allergens to the skin for 48 hours.

With a skin test, an allergist can check for these kinds of allergies:

• environmental, such as mold, pet dander, or tree pollen
• food, such as peanuts or eggs
• medicines, such as penicillin

Some medicines (such as antihistamines) can interfere with skin testing, so check with the doctor to see if your child’s medications need to be stopped before the test is done. While skin testing is useful and helpful, sometimes more tests (like blood tests or food challenges) also must be done to see if a child is truly allergic to something.

While skin tests are usually well tolerated, in rare instances they can cause a more serious allergic reaction. This is why skin testing must always be done in an allergist’s office, where the doctor is prepared to handle a reaction.

What is the difference between food allergies and food intolerances?
– Elaine

Food allergies and food intolerances (or sensitivities) can have similar symptoms, but are very different conditions:

• Intolerances, such as lactose intolerance and celiac disease, can cause someone to feel ill.
• Food allergies not only can make someone feel ill, but also can cause a life-threatening reaction (called anaphylaxis).

A food intolerance means either the body cannot properly digest the food that is eaten, or that a particular food might irritate the digestive system. Symptoms of food intolerance can include nausea, gas, cramps, abdominal pain, diarrhea, irritability, nervousness, or headaches.

A food allergy happens when the body’s immune system, which normally fights infections, sees the food as an invader. This leads to an allergic reaction — a response from the immune system in which chemicals like histamine are released in the body. The reaction can cause symptoms like breathing problems, throat tightness, hoarseness, coughing, vomiting, abdominal pain, hives, swelling, or a drop in blood pressure.

Even if previous reactions have been mild, someone with a food allergy is always at risk of the next reaction being life-threatening. Eating a microscopic amount of the food, or sometimes even touching or inhaling it, could lead to anaphylaxis. So anyone with a food allergy must avoid the problem food(s) entirely and always carry emergency injectable epinephrine.

Many people with food sensitivities, on the other hand, can ingest a small amount of the bothersome food without a problem.

About Wheat Allergy

When someone is allergic to wheat, the body’s immune system, which normally fights infections, overreacts to proteins in the wheat. When the person eats something made with wheat, the body thinks that these proteins are harmful invaders.

The immune system responds by working very hard to fight off the invader. This causes an allergic reaction, in which chemicals like histamine are released in the body. The release of these chemicals can cause someone to have these symptoms:

• wheezing
• trouble breathing
• coughing
• hoarseness
• throat tightness
• stomachache
• vomiting
• diarrhea
• itchy, watery, or swollen eyes
• hives
• red spots
• swelling
• a drop in blood pressure, causing lightheadedness or loss of consciousness

Allergic reactions to wheat can differ. Sometimes the same person can react differently at different times. Some reactions can be very mild and involve only one system of the body, like hives on the skin. Other reactions can be more severe and involve more than one part of the body.

Wheat Allergy and Celiac Disease Are Different

An allergy to wheat involves an allergic response to a protein in wheat. Gluten is one of the wheat proteins that can cause an allergic reaction. Gluten is also involved in a condition called celiac disease.

It’s easy to confuse celiac disease with wheat allergy, but they are very different. Celiac disease does not cause an allergic reaction. With celiac disease, there is a different type of immune system response in the intestines, causing a problem with the absorption of food.

While people with wheat allergy can usually eat other grains, people with celiac disease cannot eat any food containing gluten, which is also found in other grains such as barley, rye, and sometimes oats.

Anaphylaxis Is a Life-Threatening Reaction

Wheat allergy can cause a severe allergic reaction called anaphylaxis. Anaphylaxis can begin with milder symptoms, but then can quickly worsen, leading to someone having trouble breathing or passing out. If it is not treated, anaphylaxis can be life-threatening.

If your child has been diagnosed with a life-threatening wheat allergy (or any kind of life-threatening food allergy), the doctor will want him or her to carry an epinephrine auto-injector in case of an emergency.

An epinephrine auto-injector is a prescription medicine that comes in an easy-to-carry container about the size of a large marker. It’s simple to use. If your child needs to have it on hand, your doctor will show you how to use it.

Kids who are old enough can be taught how to give themselves the injection. If they are responsible for carrying the epinephrine, it should be nearby, not locked in a locker or in the nurse’s office.

Wherever your child is, adult caregivers should always know where the epinephrine is, have easy access to it, and know how to give the shot. Staff at your child’s school should know about the allergy and have an action plan in place. Your child’s rescue medications (such as epinephrine) should be accessible at all times.

If your child starts having serious allergic symptoms, like swelling of the mouth or throat or difficulty breathing, give the epinephrine auto-injector right away. Seconds count during an episode of anaphylaxis. Then call 911 or take your child to the emergency room. Your child needs to be under medical supervision because even if the worst seems to have passed, it’s common for a second wave of serious symptoms to happen.

It’s also a good idea to carry an over-the-counter (OTC) antihistamine for your child as this can help treat mild allergy symptoms. Use antihistamines after — not as a replacement for — the epinephrine shot during life-threatening reactions.

Living With Wheat Allergy

If allergy testing shows that your child has a wheat allergy, the doctor will provide guidelines on how to stay safe. Wheat allergy is more common in kids than adults, and many children seem to “outgrow” their wheat allergy over time.

But if your your child has wheat allergy, he or she must completely avoid products made with wheat. Although most allergic reactions to wheat occur after eating a wheat product, sometimes people can react to raw wheat that they breathe in (such as a baker who inhales flour in the workplace).

Natural food stores and the health food section in grocery stores usually have safe alternatives, including wheat-free breads, crackers, and breakfast cereals. Also, look for substitute flours made from potato, rice, soy, barley, oats, and corn.

For detailed information, visit food allergy websites, such as the Food Allergy Research and Education network (FARE), or others that your doctor recommends.

Manufacturers of foods sold in the United States must state in understandable language whether foods contain any of the top eight most common allergens: wheat, milk, egg, fish, crustacean shellfish, peanuts, tree nuts, and soy.

The label will include “wheat” in the ingredient list or say “Contains wheat” after the list. This label requirement makes things a little easier. But you still may want to learn the names of some common ingredients, such as durum, that mean wheat.

Cross-Contamination

Cross-contamination means that the allergen is not one of the ingredients in a product, but might have contaminated it during production or packaging. Companies are not required to label for cross-contamination risk, though some voluntarily do so. You may see advisory statements such as “May contain wheat,” “Processed in a facility that also processes wheat,” or “Manufactured on equipment also used for wheat.”

Since products without precautionary statements also might be cross-contaminated and the company simply chose not to label for it, it is always best to contact the company to see if the product could contain wheat. You might find this information on the company’s website or you can contact a company representative via email.

It’s also important to remember that “safe” foods could become unsafe if food companies change ingredients, processes, or production locations.

Eating Away From Home

When your child eats in a restaurant or at a friend’s house, find out how foods are cooked and exactly what’s in them. It can be hard to ask a lot of questions about cooking methods, and to trust the information you get. If you can’t be certain that a food is wheat-free, it’s best to bring safe food from home.

Watch for cross-contamination, as wheat can get into a food product because it is made or served in a place that uses wheat in other foods. This can happen on kitchen surfaces and utensils — everything from knives and cutting boards to a toaster or grill. Fried foods often have the potential to be cross-contaminated, because they can be fried in the same oil as foods that contain wheat.

Also talk to the staff at school about cross-contamination risks in the cafeteria. It may be best to pack lunches at home so you can control what’s in them.

Here are some other precautions to take:

• Don’t feed your child cooked foods you didn’t make yourself — or anything else with unknown ingredients.
• Tell everyone who handles the food — from relatives to restaurant waitstaff — that your child has a wheat allergy.
• Make school lunches and snacks at home where you can control the preparation.
• If the manager or owner of a restaurant is uncomfortable about your request for wheat-free food preparation, don’t eat there.