Food allergy is treated by avoiding the foods that trigger the reaction. Once you and your healthcare provider have identified the food(s) to which you are sensitive, you must remove them from your diet. To do this, you must read the detailed ingredient lists on each food you are considering eating.

Many allergy-producing foods such as peanuts, eggs, and milk, appear in foods one normally would not associate them with. Peanuts, for example, may be used as a protein source, and eggs are used in some salad dressings.

Because of a new law in the United States, FDA now requires ingredients in a packaged food to appear on its label. You can avoid most of the things to which you are sensitive if you read food labels carefully and avoid restaurant-prepared foods that might have ingredients to which you are allergic.

If you are highly allergic, even the tiniest amounts of a food allergen (for example, a small portion of a peanut kernel) can prompt an allergic reaction.

If you have food allergies, you must be prepared to treat unintentional exposure. Even people who know a lot about what they are sensitive to occasionally make a mistake. To protect yourself if you have had allergic reactions to a food, you should

• Wear a medical alert bracelet or necklace stating that you have a food allergy and are subject to severe reactions
• Carry an auto-injector device containing epinephrine (adrenaline), such as an epipen or twinject, that you can get by prescription and give to yourself if you think you are getting a food allergic reaction
• Seek medical help immediately, even if you have already given yourself epinephrine, by either calling the rescue squad or by getting transported to an emergency room

Anaphylactic allergic reactions can be fatal even when they start off with mild symptoms such as a tingling in the mouth and throat or GI discomfort.

Exercise-Induced Food Allergy

At least one situation may require more than simply eating food with allergens to start a reaction: exercise-induced food allergy. People who have this reaction only experience it after eating a specific food before exercising. Some people get this reaction from many foods, and others get it only after eating a specific food. As exercise increases and body temperature rises, itching and light-headedness start and allergic reactions such as hives may appear and even anaphylaxis may develop.

The management of exercised-induced food allergy is simple—avoid eating for a couple of hours before exercising.

Schools and daycare centers must have plans in place to address any food allergy emergency. Parents and caregivers should take special care with children and learn how to

• Protect children from foods to which they are allergic
• Manage children if they eat a food to which they are allergic
• Give children epinephrine

Simply washing your hands with soap and water will remove peanut allergens. Also, most household cleaners will remove them from surfaces such as food preparation areas at home as well as daycare facilities and schools. These easy-to-do measures will help prevent peanut allergy reactions in children and adults.

There are several medicines you can take to relieve food allergy symptoms that are not part of an anaphylactic reaction. These include

Antihistamines to relieve GI symptoms, hives, or sneezing and a runny nose

Bronchodilators to relieve asthma symptoms

It is not easy to determine if a reaction to food is anaphylactic, however. It is important to develop a plan with a healthcare provider as to what reactions you should treat with epinephrine first, rather than antihistamines or bronchodilators.

Controversial and Unproven Treatments

One controversial treatment, which sometimes may be used with provocative challenge, includes putting a diluted solution of a particular food under your tongue about a half hour before you eat the food suspected of causing an allergic reaction. This is an attempt to “neutralize� the subsequent exposure to the food you believe is harmful. The results of carefully conducted clinical research show this procedure does not prevent an allergic reaction.

Allergy shots

Another unproven treatment involves getting allergy shots (immunotherapy) containing small quantities of the food extracts to which you are allergic. These shots are given regularly for a long period of time with the aim of “desensitizing� you to the food allergen. Researchers have not yet proven that allergy shots reliably relieve food allergies.

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After ruling out food intolerances and other health problems, your healthcare provider will use several steps to find out if you have an allergy to specific foods.

Detailed History

A detailed history is the most valuable tool for diagnosing food allergy. Your provider will ask you several questions and listen to your history of food reactions to decide if the facts fit a food allergy.

• What was the timing of your reaction?
• Did your reaction come on quickly, usually within an hour after eating the food?
• Did allergy medicines help? Antihistamines should relieve hives, for example.
• Is your reaction always associated with a certain food?
• Did anyone else who ate the same food get sick? For example, if you ate fish contaminated with histamine, everyone who ate the fish should be sick.
• How much did you eat before you had a reaction? The severity of a reaction is sometimes related to the amount of food eaten.
• How was the food prepared? Some people will have a violent allergic reaction only to raw or undercooked fish. Complete cooking of the fish may destroy the allergen, and they can then eat it with no allergic reaction.
• Did you eat other foods at the same time you had the reaction? Some foods may delay digestion and thus delay the start of the allergic reaction.

Diet Diary

Sometimes your healthcare provider can’t make a diagnosis solely on the basis of your history. In that case, you may be asked to record what you eat and whether you have a reaction. This diet diary gives more detail from which you and your provider can see if there is a consistent pattern in your reactions.

Elimination Diet

The next step some healthcareproviders use is an elimination diet.In this step, which is done under your provider’s direction, certain foods are removed from your diet. You don’t eat a food suspected of causing the allergy, such as eggs. You then substitute another food—in the case of eggs, another source of protein.

Your provider can almost always make a diagnosis if the symptoms go away after you remove the food from your diet. The diagnosis is confirmed if you then eat the food and the symptoms come back. You should do this only when the reactions are not significant and only under healthcare provider direction.

Your provider can’t use this technique, however, if your reactions are severe or don’t happen often. If you have a severe reaction, you should not eat the food again.

Skin Test

If your history, diet diary, or elimination diet suggests a specific food allergy is likely, your healthcare provider will then use either the scratch or the prick skin test to confirm the diagnosis.

During a scratch skin test, your healthcare provider will place an extract of the food on the skin of your lower arm. Your provider will then scratch this portion of your skin with a needle and look for swelling or redness, which would be a sign of a local allergic reaction.

A prick skin test is done by putting a needle just below the surface of your skin of the lower arm. Then, a tiny amount of food extract is placed under the skin.

If the scratch or prick test is positive, it means that there is IgE on the skin’s mast cells that is specific to the food being tested. Skin tests are rapid, simple, and relatively safe. You can have a positive skin test to a food allergen, however, without having an allergic reaction to that food. A healthcare provider diagnoses a food allergy only when someone has a positive skin test to a specific allergen and when the history of reactions suggests an allergy to the same food.

Blood Test

Your healthcare provider can make a diagnosis by doing a blood test as well. Indeed, if you are extremely allergic and have severe anaphylactic reactions, your provider can’t use skin testing because causing an allergic reaction to the skin test could be dangerous. Skin testing also can’t be done if you have eczema over a large portion of your body.

Your healthcare provider may use blood tests such as the RAST (radioallergosorbent test) and newer ones such as the CAP-RAST. Another blood test is called ELISA (enzymelinked immunosorbent assay). These blood tests measure the presence of food-specific IgE in your blood. The CAP-RAST can measure how much IgE your blood has to a specific food. As with skin testing, positive tests do not necessarily mean you have a food allergy.

Double-Blind Oral Food Challenge

The final method healthcare providers use to diagnose food allergy is double-blind oral food challenge.

Your healthcare provider will give you capsules containing individual doses of various foods, some of which are suspected of starting an allergic reaction. Or your provider will mask the suspected food within other foods known not to cause an allergic reaction. You swallow the capsules one at a time or swallow the masked food and are watched to see if a reaction occurs.

In a true double-blind test, your healthcare provider is also “blinded� (the capsules having been made up by another medical person). In that case your provider does not know which capsule contains the allergen.

The advantage of such a challenge is that if you react only to suspected foods and not to other foods tested, it confirms the diagnosis. You cannot be tested this way if you have a history of severe allergic reactions.

In addition, this testing is difficult because it takes a lot of time to perform and many food allergies are difficult to evaluate with this procedure. Consequently, many healthcare providers do not perform double-blind food challenges.

This type of testing is most commonly used if a healthcare provider thinks the reaction described is not due to a specific food and wishes to obtain evidence to support this. If your provider finds that your reaction is not due to a specific food, then additional efforts may be used to find the real cause of the reaction.

Controversial and Unproven Diagnostic Methods

Cytotoxicity testing

One controversial diagnostic technique is cytotoxicity testing, in which a food allergen is added to a blood sample. A technician then examines the sample under the microscope to see if white cells in the blood “die.� Scientists have evaluated this technique in several studies and have found it does not effectively diagnose food allergy.

Provocative challenge

Another controversial approach is called sublingual (placed under the tongue) or subcutaneous (injected under the skin) provocative challenge. In this procedure, diluted food allergen is put under your tongue if you feel that your arthritis, for instance, is due to foods. The technician then asks you if the food allergen has made your arthritis symptoms worse. In clinical studies, researchers have not shown that this procedure can effectively diagnose food allergy.

Sublingual provocative challenge is not the same as a potentiallynew treatment for food allergy called sublingual immunotherapyor SLIT. Researchers are currently evaluating this treatment.

Immune complex assay

An immune complex assay is sometimes done on people suspected of having food allergies to see if groups, or complexes, of certain antibodies connect to the food allergen in the bloodstream. Some think that these immune groups link with food allergies. The formation of such immune complexes is a normal offshoot of food digestion, however, and everyone, if tested with a sensitive-enough measurement, has them. To date, no one has conclusively shown that this test links with allergies to foods.

IgG subclass assay

Another test is the IgG subclass assay, which looks specifically for certain kinds of IgG antibody. Again, there is no evidence that this diagnoses food allergy.

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