Food Allergy 

An Overview

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

National Institutes of Health 

National Institute of Allergy and Infectious Diseases 
Food Allergy
 An Overview

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

National Institutes of Health 

National Institute of Allergy and Infectious Diseases 

NIH Publication No. 07-5518 

July 2007 

www.niaid.nih.gov 
Contents


1 Introduction


2 What Is Food Allergy?


3 How Do Allergic Reactions Work?


6 Common Food Allergies


7 Food Allergy or Food Intolerance?


11 Diagnosis 

16 Treatment 

19 Food Allergy in Infants and Children 

21 Some Controversial and 

Unproven Theories 

25 Research 

27 More Information 

31 Glossary 

Introduction


Food allergy affects up to 6 to 8 percent of children under 

the age of 3 and close to 4 percent of adults. If you have 

an unpleasant reaction to something you have eaten, you 

might wonder if you have a food allergy. One out of three 

people either believe they have a food allergy or modify their 

or their family’s diet. Thus, while food allergy is commonly 

suspected, healthcare providers diagnose it less frequently 

than most people believe. 

This pamphlet describes allergic reactions to foods and their 

possible causes as well as the best ways to diagnose and treat 

allergic reactions to food. It also describes other reactions to 

foods, known as food intolerances, which can be confused with 

food allergy, and describes some unproven and controversial 

food allergy theories. 

1 
What Is Food Allergy?


Food allergy is an abnormal response to a food triggered by 

the body’s immune system. In this pamphlet, food allergy 

refers to a particular type of response of the immune system 

in which the body produces what is called an allergic, or IgE, 

antibody to a food. (IgE, or immunoglobulin E, is a type 

of protein that works against a specific food.) 

Allergic reactions to food can cause serious illness and, in 

some cases, death. Therefore, if you have a food allergy, it is 

extremely important for you to work with your healthcare 

provider to find out what food(s) causes your allergic reaction. 

Sometimes, a reaction to food is not an allergy at all but 

another type of reaction called “food intolerance.” 

Food intolerance is more common than food allergy. The 

immune system does not cause the symptoms of food 

intolerance, though these symptoms may look and feel 

like those of a food allergy. 

2 

Note: Words in bold are defined in the glossary at the end of 

this booklet. 
How Do Allergic Reactions Work?


An immediate allergic reaction involves two actions of your 

immune system 

•	 Your immune system produces IgE. This protein is 

called a food-specific antibody, and it circulates through 

your blood. 

•	 The food-specific IgE then attaches to mast cells and 

basophils. Basophils are found in blood. Mast cells 

are found in body tissues, especially in areas of your 

body that are typical sites of allergic reactions. Those 

sites include your nose, throat, lungs, skin, and 

gastrointestinal (GI) tract. 

Generally, your immune system will form IgE against a food 

if you come from a family in which allergies are common 

—not necessarily food allergies but perhaps other allergic 

diseases, such as hay fever or asthma. If you have two allergic 

parents, you are more likely to develop food allergy than 

someone with one allergic parent. 

If your immune system is inclined to form IgE to certain 

foods, you must be exposed to the food before you can have 

an allergic reaction. 

As this food is digested, it triggers certain cells in your 

body to produce a food-specific IgE in large amounts. 

The food-specific IgE is then released and attaches to the 

surfaces of mast cells and basophils. 

•	 The next time you eat that food, it interacts with 

food-specific IgE on the surface of the mast cells and 

basophils and triggers those cells to release chemicals 

such as histamine. 

3 
•	 Depending on the tissue in which they are released, 

these chemicals will cause you to have various symptoms 

of food allergy. 

Food allergens are proteins in the food that enter your 

bloodstream after the food is digested. From there, they 

go to target organs, such as your skin or nose, and cause 

allergic reactions. 

An allergic reaction to food can take place within a few 

minutes to an hour. The process of eating and digesting 

food affects the timing and the location of a reaction. 

•	 If you are allergic to a particular food, you may first 

feel itching in your mouth as you start to eat the food. 

•	 After the food is digested in your stomach, you may 

have GI symptoms such as vomiting, diarrhea, or pain. 

•	 When the food allergens enter and travel through your 

bloodstream, they may cause your blood pressure to drop. 

•	 As the allergens reach your skin, they can cause hives 

or eczema. 

•	 When the allergens reach your mouth and lungs, they 

may cause throat tightness and trouble breathing. 

4 
Cross-Reactive Food Allergies 

If you have a life-threatening reaction to a certain food, 

your healthcare provider will show you how to avoid similar 

foods that might trigger this reaction. For example, if you 

have a history of allergy to shrimp, allergy testing will usually 

show that you are not only allergic to shrimp but also to 

crab, lobster, and crayfish. This is called “cross-reactivity.” 

Another interesting example of cross-reactivity occurs in 

people who are highly sensitive to ragweed. During ragweed 

pollen season, they sometimes find that when they try to 

eat melons, particularly cantaloupe, they experience itching 

in their mouths and simply cannot eat the melon. Similarly, 

people who have severe birch pollen allergy also may react 

to apple peels. This is called the “oral allergy syndrome.” 

5 
Common Food Allergies


In adults, the foods that most often cause allergic 

reactions include 

• Shellfish such as shrimp, crayfish, lobster, and crab 

• Peanuts 

• Tree nuts such as walnuts 

• Fish 

• Eggs 

The most common foods 

that cause problems in children are 

• Eggs 

• Milk 

• Peanuts 

• Tree nuts 

Peanuts and tree nuts are the leading causes of the potentially 

deadly food allergy reaction called anaphylaxis. 

Adults usually keep their allergies for life, but children 

sometimes outgrow them. Children are more likely to 

outgrow allergies to milk, egg, or soy, however, than 

allergies to peanuts. The foods to which adults or children 

usually react are those foods they eat often. In Japan, for 

example, rice allergy is frequent. In Scandinavia, codfish 

allergy is common. 

6 
Food Allergy or Food Intolerance?


If you go to your healthcare provider and say, “I think I 

have a food allergy,” your provider has to consider other 

possibilities that may cause symptoms and could be confused 

with food allergy, such as food intolerance. To find out the 

difference between food allergy and food intolerance, your 

provider will go through a list of possible causes for your 

symptoms. This is called a “differential diagnosis.” This type 

of diagnosis helps confirm that you do indeed have a food 

allergy rather than a food intolerance or other illness. 

Types of Food Intolerance 

Food poisoning 

One possible cause of symptoms like those of food allergy 

is food contaminated with microbes, such as bacteria, and 

bacterial products, such as toxins. Contaminated meat and 

dairy products sometimes cause symptoms, including GI 

discomfort, that resemble a food allergy when it is really a 

type of food poisoning. 

Histamine toxicity 

There are substances, such as the powerful chemical histamine, 

present in certain foods that cause a reaction similar to an 

allergic reaction. For example, histamine can reach high levels 

in cheese, some wines, and certain kinds of fish such as tuna 

and mackerel. 

In fish, histamine is believed to come from contamination by 

bacteria, particularly in fish that are not refrigerated properly. 

If you eat one of these foods with a high level of histamine, 

7 
you could have a reaction that strongly resembles an allergic 

reaction to food. This reaction is called “histamine toxicity.” 

Lactose intolerance 

Another cause of food intolerance confused with a food allergy 

is lactose intolerance or lactase deficiency. This common food 

intolerance affects at least 1 out of 10 people. 

Lactase is an enzyme that is in the lining of your gut. Lactase 

breaks down or digests lactose, a sugar found in milk and most 

milk products. 

Lactose intolerance, or lactase deficiency, happens when there 

is not enough lactase in your gut to digest lactose. In that 

case, bacteria in your gut use lactose to form gas which causes 

bloating, abdominal pain, and sometimes diarrhea. 

Your healthcare provider can use laboratory tests to find out 

whether your body can digest lactose. 

Food additives 

Another type of food intolerance is a reaction to certain 

products that are added to food to enhance taste, provide 

color, or protect against the growth of microbes. Several 

chemical compounds, such as MSG (monosodium glutamate) 

and sulfites, are tied to reactions that can be confused with 

food allergy. 

8 
MSG 

MSG is a flavor enhancer and, when taken in large 

amounts, can cause some of the following signs: 

• Flushing 

• Sensations of warmth 

• Headache 

• Chest discomfort 

• Feelings of detachment 

These passing reactions occur rapidly after eating large 

amounts of food to which MSG has been added. 

Sulfites in high concentrations sometimes pose 

problems for people with severe asthma. Sulfites 

can give off a gas called sulfur dioxide that a 

person with asthma inhales while eating food 

containing sulfites. This gas irritates the 

lungs and can send an asthmatic into 

severe bronchospasm, a tightening of 

the lungs.

The Food and Drug Administration 

(FDA) has banned sulfites as spray-on 

preservatives in fresh fruits and vegetables. 

Sulfites are still used in some foods, 

however, and occur naturally during 

the fermentation of wine. 

Sulfites 

Sulfites occur naturally in foods or may be added to 

increase crispness or prevent mold growth. 

9 
Gluten intolerance 

Gluten intolerance is associated with the disease called 

“gluten-sensitive enteropathy” or “celiac disease.” It happens 

if your immune system responds abnormally to gluten, which 

is a part of wheat and some other grains. Some researchers 

include celiac disease as a food allergy. This abnormal immune 

system response, however, does not involve IgE antibody. 

Psychological causes 

Some people may have a food intolerance that has a psychological trigger. If your food intolerance is caused by this type 

of trigger, a careful psychiatric evaluation may identify an 

unpleasant event in your life, often during childhood, tied to 

eating a particular food. Eating that food years later, even as 

an adult, is associated with a rush of unpleasant sensations. 

Other causes 

There are several other conditions, including ulcers and 

cancers of the GI tract, that cause some of the same symptoms 

as food allergy. These symptoms include vomiting, diarrhea, 

and cramping abdominal pain made worse by eating. 

10 
Diagnosis


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. 

11 
asked to record what you eat and whether you have 

Diet Diary 

Sometimes your healthcare provider can’t make a diagnosis 

solely on the basis of your history. In that case, you may be 

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 healthcare


providers 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. 

12 
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 

13 
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 

14 
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. 

15 
Treatment


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 

16 
•	 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. 

17 
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. 

18 
Food Allergy in Infants and Children


Allergy to cow’s milk is particularly 

common in infants and young 

children. It causes hives and asthma 

in some children. In others, it can 

lead to colic and sleeplessness, and 

perhaps blood in the stool or poor 

growth. Infants are thought to be 

particularly susceptible to this allergic 

syndrome because their immune 

and digestive systems are 

immature. Milk allergy can 

develop within days to months of birth. 

If your baby is on cow’s milk formula, your healthcare 

provider may suggest a change to soy formula or an elemental 

formula if possible. Elemental formulas are produced from 

processed proteins with supplements added (basically sugars 

and amino acids). There are few if any allergens within 

these materials. 

Healthcare providers sometimes prescribe glucocorticosteroid 

medicines to treat infants with very severe GI reactions to milk 

formulas. Fortunately, this food allergy tends to go away 

within the first few years of life. 

Breast feeding often helps babies avoid feeding problems 

related to allergic reactions. Therefore, health experts often 

suggest that mothers feed their baby only breast milk for 

the first months of life to avoid milk allergy from developing 

within that timeframe. 

19 
Some babies are very sensitive to a certain food. If you are 

nursing and eat that food, sufficient amounts can enter your 

breast milk to cause a food reaction in your baby. To keep 

possible food allergens out of your breast milk, you might 

try not eating those foods, such as peanuts, that could cause 

an allergic reaction in your baby. 

There is no conclusive evidence that breastfeeding prevents 

allergies from developing later in your child’s life. It does, 

however, delay the start of food allergies by delaying your 

infant’s exposure to those foods that can prompt allergies. Plus, 

it may avoid altogether food allergy problems sometimes seen 

in infants. 

By delaying the introduction of solid foods until your baby 

is 6 months old or older, you can also prolong your baby’s 

allergy-free period. Speak to your healthcare provider for 

specific instructions on when to add specific food groups 

to your child’s diet. 

20 
Some Controversial and Unproven Theories


Controversial and Unproven Disorders 

There are several disorders that are popularly thought by 

some to be caused by food allergies. 

Either there is not enough scientific 

evidence to support those claims, 

or there is evidence that goes against 

such claims. 

Migraine headaches 

There is controversy about whether 

migraine headaches can be caused 

by food allergy. Studies show people 

who are prone to migraines can have 

their headaches brought on by histamine and other 

substances in foods. The more difficult issue is whether food 

allergies actually cause migraines in such people. 

Arthritis 

There is virtually no evidence that most rheumatoid arthritis 

or osteoarthritis can be made worse by foods, despite claims 

to the contrary. 

Allergic tension fatigue syndrome 

There is no evidence that food allergies can cause a disorder 

called the allergic tension fatigue syndrome, in which people 

are tired, nervous, and may have problems concentrating or 

have headaches. 

21 
Cerebral allergy 

Cerebral allergy is a term that has been given to people 

who have trouble concentrating and have headaches as well 

as other complaints. These symptoms are sometimes blamed 

on mast cells activated in the brain but no other place in 

the body. Researchers have found no evidence that such a 

scenario can happen. Most health experts do not recognize 

cerebral allergy as a disorder. 

Environmental illness 

In a seemingly pristine environment, some people have many 

nonspecific complaints such as problems concentrating or 

depression. Sometimes this is blamed on small amounts of 

allergens or toxins in the environment. There is no evidence 

that these problems are due to food allergies. 

Childhood hyperactivity 

Some people believe hyperactivity in children is caused by 

food allergies. Researchers, however, have found that this 

behavioral disorder in children is only occasionally associated 

with food additives, and then only when such additives are 

consumed in large amounts. 

There is no evidence that a true food allergy can affect a child’s 

activity except for the possibility that if a child itches and 

sneezes and wheezes a lot, the child may be uncomfortable 

and therefore more difficult to guide. Also, children who are 

on anti-allergy medicines that cause drowsiness may get 

sleepy in school or at home. 

22 
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 potentially


new treatment for food allergy called sublingual immunotherapy


or 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 

23 
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. 

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. 

24 
Research


The National Institute of Allergy and Infectious Diseases 

conducts research on food allergy and other allergic diseases. 

This research is focused on understanding what happens to 

the body during the allergic process—the sequence of events 

leading to the allergic response and the factors responsible 

for allergic diseases. This understanding will lead to better 

methods of diagnosing, preventing, and treating allergic 

diseases. Researchers also are looking at better ways to study 

allergic reactions to foods. 

Educating people, including patients, healthcare providers, 

school teachers, and daycare workers, about the importance 

of food allergy is also an important research focus. The more 

people know about the disorder, 

the better equipped they will 

be to control food allergies. 

Several treatment approaches 

are currently being tested in 

research settings. 

Immunotherapy with Allergen 

Injections 

One potential treatment for food allergy involves getting 

injections or shots (immunotherapy) subcutaneously (under 

the skin) that contain small quantities of the food extracts to 

which a person is allergic. These shots are given regularly for 

a long period of time with the aim of increasing the ability 

to tolerate the food allergen. Researchers have not yet found 

a safe and effective way to give allergens subcutaneously, 

because people often have allergic reactions to these injections. 

25 
Immunotherapy with Allergen Under the Tongue 

Another potential treatment for food allergy involves putting 

allergens under the tongue, called sublingual immunotherapy 

(SLIT). Researchers think this is safer than giving under the 

skin. As of mid-2007, however, this treatment was only in 

very early stages. 

Anti-IgE Therapy 

One published study suggested that some (but not all) people 

with peanut allergy might be partially protected against allergic 

reactions to low doses of peanut by taking regular subcutaneous 

injections of one particular form of a medicine called anti-IgE. 

Because the FDA-approved anti-IgE medicine has not yet 

been tested for peanut allergy, this treatment is not currently 

available for peanut allergy. Scientists need to do further 

research to determine the value of anti-IgE. 

26 
More Information


National Institute of Allergy and Infectious Diseases 

6610 Rockledge Drive, MSC 6612 

Bethesda, MD 20892-6612 

301–496–5717 

www.niaid.nih.gov 

National Library of Medicine 

MedlinePlus 

8600 Rockville Pike 

Bethesda, MD 20894 

1–888–FIND–NLM (1–888–346–3656) or 301–594–5983 

www.medlineplus.gov 

American Academy of Allergy, Asthma & Immunology 

555 East Wells Street, Suite 1100 

Milwaukee, WI 53202-3823 

1–800–822–ASMA (1–800–822–2762) 

www.aaaai.org 

The American Academy of Pediatrics 

141 Northwest Point Boulevard 

Elk Grove Village, IL 60007-1098 

847–434–4000 

www.aap.org 

American College of Allergy, Asthma & Immunology 

85 West Algonquin Road, Suite 550 

Arlington Heights, IL 60005 

1–800–842–7777 

www.acaai.org 

27 
Asthma and Allergy Foundation of America 

1233 20th Street, NW, Suite 402 

Washington, DC 20036 

1–800–7–ASTHMA (1–800–727–8462) or 202–466–7643 

www.aafa.org 

The Food Allergy and Anaphylaxis Network 

11781 Lee Jackson Highway, Suite 160 

Fairfax, VA 22033 

1–800–929–4040 

www.foodallergy.org 

Allergy Extracts 

Food and Drug Administration 

Center for Biologics Evaluation and Research 

1401 Rockville Pike 

Rockville, MD 20852-1448 

1–800–835–4709 or 301–827–1800 

www.fda.gov/cber 

Celiac Disease and Lactose Intolerance 

National Institute of Diabetes and Digestive and 

Kidney Diseases 

National Digestive Diseases Information Clearinghouse 

2 Information Way 

Bethesda, MD 20892-3570 

1–800–891–5389 

www.digestive.niddk.nih.gov 

28 
Eczema 

National Arthritis and Musculoskeletal and Skin Diseases 

Information Clearinghouse 

1 AMS Circle 

Bethesda, MD 20892-3675 

1–877–22–NIAMS (1–877–226–4267) or 301–495–4484 

www.niams.nih.gov 

American Academy of Dermatology 

P.O. Box 4014 

Schaumburg, IL 60168-4014 

847–330–0230 

www.aad.org 

National Eczema Association for Science and Education 

4460 Redwood Highway, Suite 16-D 

San Rafael, CA 94903-1953 

1–800–818–7546 or 415–499–3474 

www.nationaleczema.org 

Food Contents 

U.S. Department of Agriculture 

Food and Nutrition Information Center 

National Agricultural Library, Room 105 

10301 Baltimore Avenue 

Beltsville, MD 20705-2351 

301–504–5719 

www.nal.usda.gov/fnic 

29 
Food Facts 

American Dietetic Association 

National Center for Nutrition and Dietetics Information Line 

1–800–366–1655 

www.eatright.org/Public 

30 
Glossary


allergens—substances that cause an allergic reaction. 

amino acids—any of the 26 building blocks of proteins. 

anaphylaxis—a severe reaction to an allergen that can cause 

itching, fainting, and in some cases, death. 

antibody—a molecule tailor-made by the immune system 

to lock onto and destroy specific foreign substances such as 

allergens. 

assay—a laboratory method of measuring a substance such 

as immunoglobulin. 

bacteria—kind of microbe, some of which can contaminate 

or spoil food. 

basophils—white blood cells that contribute to inflammatory 

reactions. 

challenge—process of assessing the immune system’s response 

to a food allergen. 

cells—the smallest units of life; the basic living things that 

make up tissues. 

celiac disease—a disease of the digestive system that 

damages the small intestine and interferes with absorption 

of nutritional contents of food. 

cytotoxicity testing—an unproven laboratory method of 

diagnosing allergies by examining blood samples under a 

microscope to see if white blood cells “die.” 

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elimination diet—certain foods are removed from a person’s 

diet and a substitute food of the same type, such as another 

source of protein in place of eggs, is introduced. 

enzyme—a protein produced by living cells that promotes 

specific biochemical reactions at body temperatures. 

epinephrine—a drug form of adrenaline (a natural hormone 

in the body) that stimulates nerves. 

extract—a concentrated liquid preparation containing minute 

parts of specific foods. 

gastrointestinal (GI) tract—an area of the body that includes 

the stomach and intestines. 

glucocorticoid—a type of steroid drug that reduces 

inflammation. 

granule—grain-like part of a cell. 

histamine—chemical released by mast cells and basophils. 

histamine toxicity—an allergic-like reaction to eating foods 

containing high levels of histamine. 

immune system—a complex network of specialized cells, 

tissues, and organs, such as the lungs, that defends the body 

against attacks by disease-causing microbes. 

immunoglobulin—one of a large family of proteins, also 

known as antibody. 

inflammation—an immune system reaction to allergens or 

germs. Signs include redness, swelling, pain, or heat. 

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lactose intolerance—the inability to digest lactose, a kind 

of sugar found in milk and other food products. Lactose 

intolerance is caused by a shortage of the enzyme lactase, 

which is produced by the cells that line the small intestine. 

microbes—tiny life forms, such as bacteria, viruses, and fungi, 

that may cause disease. 

mast cells—large granule-containing cells found in body 

tissues that are typical sites of allergic reactions. 

molecule—building block of a cell; examples are proteins, 

fats, and carbohydrates. 

provocative challenge—an unproven test in which diluted 

food allergen is placed under the tongue or injected under 

the skin to find out whether symptoms get worse. 

tissues—groups of similar cells joined to perform the same 

function. 

toxins—agents produced by plants and bacteria that are 

poisonous and that also may trigger allergic reactions. 

33 
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

National Institutes of Health 

National Institute of Allergy and Infectious Diseases 

NIH Publication No. 07-5518 

July 2007 

www.niaid.nih.gov