Food Reactions

Do your symptoms include:

  • Hives
  • Swelling reactions
  • Eczema
  • Itching of the mouth, throat, skin, palms, soles, genitals
  • Feeling of warmth, feeling of “doom”
  • Vomiting, diarrhea, abdominal pain cramping
  • Food induced gastrointestinal symptoms
    • Bloating
    • Gas
    • Abdominal pain
  • Food induced respiratory symptoms*
    • Nasal congestion
    • Shortness of breath, chest tightness, cough, congestion

*It is uncommon to have food induced respiratory symptoms alone without skin or gastrointestinal symptoms

  • Dizziness, feeling faint, passing out

With proper testing (food allergy testing and challenges) and comprehensive evaluation, we can identify the food or preservatives that may be making you sick and help you find relief.

“Food allergies” are often blamed for any adverse reactions before, after or during the ingestion of a specific food. In reality, only a portion of these cases qualify as true allergic reactions, in which a food containing an allergen actually triggers an immunologic reaction, causing symptoms in the person ingesting the food. In fact, less than 8 percent of children under age 3 and about 4 percent of adults have true food allergies. 
More often than not, reactions to specific foods are due to a food intolerance rather than food allergy. Types of food allergies (IgE and non IgE mediated) and food intolerance share many common symptoms. Therefore, careful evaluation of all food-induced reactions can help avoid a misdiagnosis.

Food Allergies

Food allergy can be either classified as IgE-mediated (e.g. anaphylaxis due to peanut exposure) or non-IgE-mediated (e.g. Celiac disease due to gluten hypersensitivity, in which cellular and other immunologic reactions cause the disease process). 
During a food allergy reaction, the immune system identifies a specific food as a foreign substance. The body then produces allergy antibodies (IgE) to attack the food identified as foreign. The next time the individual ingests even a small amount of that food, these specific IgE antibodies bind to the offending food, triggering an immunologic release of chemical mediators from mast cells and other inflammatory cells, causing the allergic reaction.  Non – IgE mediated food allergies involve other specialized cells that induce allergic inflammation.  Such mechanisms play a role in atopic dermatitis and certain allergic gastrointestinal disorders like eosinophilic esophagitis.

Types of Food Intolerance (NonAllergic)

  • Absence of an enzyme needed to fully digest a food. A common example of this type of food intolerance is lactase deficiency, resulting in lactose intolerance. It can cause bloating, cramping, diarrhea and excess gas following ingestion of dairy products.
  • Irritable bowel syndrome. This recurrent or chronic condition is often associated with cramping, constipation and diarrhea following meals. Symptoms may arise from the inability of gut bacteria to breakdown certain sugar carbohydrates and sugar alcohols.
  • Food poisoning. This adverse reaction to food is commonly caused by consuming bacteria or toxins in spoiled foods (e.g. scromboid poisoning in tuna steaks, and cicatera poisoning in grouper or red snapper). Symptoms include explosive diarrhea and severe abdominal cramps (symptoms are short-lived and usually not recurrent).
  • Sensitivity to food additives. Allergy-like reactions can occur after eating certain food additives. For example, sulfites—a preservative common to dried fruit, canned goods and wine—can trigger asthma or anaphylaxis in sensitive people. Monosodium glutamate (MSG) causes flushing and hypotension, otherwise known as “Chinese restaurant syndrome.”
  • Recurring stress or psychological factors. The mere thought of a food or fear of food allergy may make people sick. Psychological triggers may manifest as GI symptoms.
  • Pharmacological reactions to foods or drinks. Caffeine can cause insomnia and palpitations. Also, tyramine in cheese can trigger migraine headache, and nausea, while peppermint and certain spices may trigger acid reflux symptoms.
  • Pseudo allergens. Certain natural substances in food can have effects similar to allergens of chemicals released in the body during a true allergic reaction. Examples are individuals may get hives from strawberries, tomatoes, pineapple, and eggplant due not to an allergen reaction to these foods but due to vasoactive constriction by the food itself.

Many Americans care about what they eat for nutritional and health reasons, however, food allergy sufferers need to be even more careful.  In some cases, eating, smelling or even touching an allergen containing food can trigger a severe and rarely fatal allergic reaction in sensitive individuals.  Food allergies do not result from digestive difficulties but rather an abnormal immune reaction usually involving allergy antibodies (IgE) as well as specialized mast cells in the gastrointestinal (GI) tract, skin, and respiratory tract. 

In fact, food allergies are defined as an adverse health effect arising from a specific immune response that occurs reproducibly on re-exposure to a given food.  This is in contrast to a food intolerance which is a non-immune reaction that includes metabolic, toxic, pharmacologic and undefined mechanisms. 

Being knowledgeable about foods and food content is of utmost importance to food allergic individuals as well as friends, family members, and those in the immediate school and work environment. Although several public information surveys show that 25% of adults believe they have some form of food allergies, studies from controlled food challenges indicate up to 8% of children have true food allergies with the incidence in adults even lower (about 5 %).  It is estimated that 2.4% of children with food allergies have multiple food allergies and 3% of children experience severe reactions from food allergies. 

Reactions to food preservatives, however, may be more common as well as intolerances to foods that may produce particular unique symptoms, particularly in the GI tract.  Over-diagnosis of food allergies is of concern because it may lead to needless dietary restrictions and/or nutritional deficiencies.  It has been suggested that food allergies may be on the rise because the food industry is using more food proteins as additives in processed foods.  These proteins were often derived from common allergic foods like milk, eggs, peanut, and soy.

Symptoms of Food Allergies

 Food allergy symptoms can occur within several seconds or hours following food ingestion, although most reactions occur within the first 2 hours.  The following symptoms can occur singly or in combination.  Hives; swelling; eczema; itching of the mouth, throat, skin, palms, soles, genitals; feeling of warmth; feeling of doom; vomiting; diarrhea; abdominal pain; cramping; nasal congestion; shortness of breath; chest tightness; cough; congestion (It is uncommon to see respiratory symptoms alone without gastrointestinal or skin symptoms.), dizziness, feeling faint, and passing out.  Aside from the physical reactions, food allergies clearly affect the quality of life of affected individuals and their psychological welfare, especially of children.

There are several symptoms that are incorrectly linked to food allergy and may be more related to pharmacologic effects to certain foods or not related to foods at all.  These include: attention deficit disorder with hyperactivity (ADHD), learning disabilities, autism, seizures, depression, bed-wetting, and fatigue.

Diagnosis of IgE Mediated Food Allergy

Careful history aimed at defining the type of reaction at the time of onset of symptoms related to food ingestion, suspect food, and related allergens are of key importance.  If a food allergy is suspected, allergy food skin testing and to a lesser extent blood food testing (ImmunoCAP) may afford some help in identifying potentially allergic foods.  Allergy food testing, however, needs to be interpreted properly.  For example, up to 50% of all positive food skin test may not represent clinically significant food allergies. 

In some cases, there is enough allergy antibody to produce a positive skin or blood test but not enough to produce an allergic reaction when eating that food.  Other immune defense mechanisms may also be at play that prevents the absorption of allergic proteins from the gut that prevent allergic reactions expressing themselves.  In other cases, the skin test or ImmunoCAP blood test remains positive in an individual who has lost symptomatic allergy to a food that can now be eaten without reaction.  On the other hand, if an allergy food skin test is negative, it is unlikely that the food can produce an IgE mediated allergic food reaction.  Blood food allergy testing (ImmunoCAP) is generally less reliable in this way with many false negative tests being observed.

To determine whether a positive food skin or blood test is clinically significant, several approaches may be taken including avoidance diets and/or food challenges in an allergist’s office.  A food challenge consists of an individual eating the suspect food under observation.  Food challenges should be done under a physician’s guidance and never performed in the home environment.  They should only be done in an office that is equipped to treat severe allergic reactions, typically in a board-certified allergist and immunologist’s office.  The other use of challenge testing is to decide whether an individual has outgrown a particular food allergy. 

Unconventional food testing through blood cytotoxic tests, sublingual food challenges, food neutralization shots, basophil histamine release, applied Kinesiology, blood allergen specific IgG4 measurement, electrodermal testing, and acupuncture testing have no scientific merit and therefore cannot be relied on for accurate diagnosis and/or treatment and are unacceptable procedures.

Common Food Allergens

Food allergies can develop at any age; however, the majority of the patients develop symptoms during childhood particularly during the first 1 to 2 years of life.  About 100 foods have been associated with severe food allergies, but a selected few account for the majority of reactions.  It is unusual for an individual to have more than 2 to 3 foods to which they are allergic.  Different foods tend to be problems with different age groups.  In young children, milk, eggs, peanut, soy, and wheat are the main culprits.  Less common foods include meats, fish, tree nuts, and other grains like barley or oat.  Older children, teenagers, and adults tend to have problems with peanuts, tree nuts, (i.e., walnuts, almonds, and pecans, etc.), shellfish, and fish.  Individuals with spring and fall hay fever may have minor but annoying allergic reactions to foods limited to itching and swelling around the lips and mouth with fresh fruits and vegetables.  Some common allergy associations between foods and pollen include apple and celery sensitivity with birch pollen allergy and cantaloupe, honeydew, watermelon, banana, and chamomile sensitivity with ragweed pollen allergy.  Development of such symptoms is known as the oral allergy syndrome and rarely causes severe allergic reactions.  Successful treatment of the respiratory symptoms due to pollen allergy with allergy injection therapy often results in reduction of the associated food allergy symptoms as well.  Individuals with latex sensitivity may also experience food reactions to cross-reactive foods such as avocado, papaya, chestnuts, and bananas.  Other food allergic reactions occur when selected individuals exercise.  This is known as food dependent exercise-induced anaphylaxis.  Reported foods that can produce these reactions include celery, shellfish, wheat, fruit, and milk, although any food may be a potential cause.

Natural History of Food Allergies

With the exception of peanut, shellfish, fish, and tree nuts, most common food allergies in infants and young children are grown out by 3 years of age as the gastrointestinal tract matures.  This is true with the vast majority of young children allergic to milk, egg, soy or wheat so that by the time a child enters kindergarten, food reactions are fortunately no longer an issue.  Strict avoidance of a known food allergen during early childhood increases the chance of outgrowing that food allergy.  Again, certain food allergies including peanut, tree nuts, fish, and shellfish are rarely outgrown.  The majority of children with egg or cow’s milk allergy can tolerate extensively heated forms of these allergens as in backed goods and ingesting these produces after a negative food challenge might actually speed recovery.


Preventing the development of food allergies may start with reducing risk factors when possible.  Ensuring adequate amounts of Vitamin D3  and  calcium in both children and pregnant women, consumption of 3-omega fatty acid and anti-oxidants, preventing obesity, and avoiding prolonged food allergen avoidance may provide some measure of prevention of some food allergies.

Regarding pregnancy diets, food allergen avoidance is no longer recommended but exclusive breast feeding for at least 4 months is advised.  For infants at risk for allergies in general, an extensively hydrolysized casein formula may offer protection against eczema over whole milk based formulas.  Prolonged avoidance of solids or specific food allergens is not protective and in fact may be a risk factor regarding development of allergies in general and food allergies in particular.  Addition of less allergic food on initiation of weaning and proceeding gradually with more allergenic foods may be helpful in some infants with eczema.  Addition of a probiotic to an infant’s /children’s diet does not prevent or treat food allergies, but may have some benefit regarding eczema.

In the case of peanut allergy prevention, there is some evidence that early introduction of peanuts at ages 4-11 months in infants at risk of development of peanut allergy may prevent peanut allergy from developing in the first 5 years of life.  In circumstances like these, such infants should be allergy skin tested and challenged in a physician’s office before starting daily peanut ingestion.

The second best treatment for food allergies is taking special care to avoid substances known to trigger reactions.  This may be very difficult to overcome despite the best of intentions and proper attention to food labeling is important but not always adequate.  FARE, the food allergy research and education organization (phone: 800-929-4040, website:, address: 7925 Jones Branch Drive, Suite 1100, McLean, VA 22102) is a nationwide support group helping individuals to identify food allergens and products and provides suggestions for alternative foods and recipes.  In special cases when allergies are present, dietary substitutions and nutritional supplements may be required.  New research is ongoing in this field, which eventually may lead to possible oral food desensitization or genetic alterations of food protein to allow for food ingestion without reaction.

In regard to children with food allergies, it is particularly important to speak with any individual that may be involved in the child’s diet including parents of a child, playmate, and teachers at school and daycare center personnel.  Also, the food allergy child should be taught early on about dietary restriction.  Eating outside the home particularly at restaurants or buying food at bakeries presents the greatest risks for food allergic individuals.  In these circumstances, ingredients are usually not listed.  Information that you may get from the restaurant server or sales person may not always be reliable.  Many people do not understand or appreciate the potential danger of food allergies and may not address questions with meticulous care and attention. 

In this regard, mistakes often occur at restaurants and at friends or relatives’ homes.  Issues of denial or carelessness may also complicate attempts at avoidance.  This is particularly true for adolescents who may be less inclined to pay strict attention to dietary avoidance.  It is particularly important to educate food allergic individuals about the life-threatening nature of their problem and prepare them for the appropriate emergency intervention required in the event of a food allergic reaction.  In addition, patients with severe food allergy reaction should wear a MedicAlert bracelet or necklace, which can be purchased through MedicAlert Foundation, (1-888-633-4298 PST; 2323 Colorado Avenue, Turlock, CA 95382, that will help to identify them as true allergic individuals.


It is often the case that despite the best efforts of avoidance, accidental ingestions occurs so food allergic individuals need to be prepared for treating these reactions.  The first step involves an emergency plan in the event of a reaction.  This plan must include medications that need to be used, exactly how much to use, and what to do if a reaction progresses.  It is possible that a plan be in effect at all times.  In regard to children, the school, daycare setting, babysitters, and other caretakers must be familiar with the plan of action as well as the parents.  Recognizing the reaction is the next important step.  Many patients who experienced food allergy will recognize the early warning symptoms such as itching of the lips, tongue and/or palms, and soles before full-blown systemic symptoms occur.  Every effort should be made to identify warning signs after a reaction.

Depending on symptoms, treatment is initially with oral antihistamines like Benadryl or Atarax as well as an injection of epinephrine.  Both the parents and child (when possible) should be familiar with the use of epinephrine.  This is a self-injectable medication, which should be available at all times.  We recommended that epinephrine be available in multiple kits for adults in the home, car, and work environment and/or purse and/or briefcase.  For a child, kits should be available in the home, in the car, and in the school environment and/or daycare center. Other medications may also be used during acute attack including oral steroids, inhalers and/or nebulizer for breathing treatments.  In the event of any severe reaction requiring the use of adrenaline and/or respiratory compromise, it is important to go immediately to the emergency room even if the reaction subsides with the initiation of treatment.  Symptoms may be lessened by the time you reach the emergency room area but it is prudent not to leave the emergency room until symptoms are completely stabilized.  With these steps in mind, food allergies can be dealt with an effective manner.

 For demonstrations of use of epinephrine autoinjector, go to and type in your autoinjector name or go to the following website(s).

EpiPen 2-PAK® (0.3mg) and EpiPen Jr 2-PAK® (0.15mg):
Auvi-Q0.3 mg (Orange Color) and Auvi-Q0.15 mg (Blue Color):
Adrenaclick® 0.3mg and Adrenaclick® 0.15mg:
Generic epinephrine autoinjector 0.3mg and 0.15mg:

Specific Food Allergy Tips



Cow’s milk is the most common food allergy in young children (both IgE- and non-IgE-mediated). Milk allergy affects 2.5% of children under age 2, with most children developing tolerance to milk by age 5. Cow’s milk contains more than 20 protein components. Milk proteins are composed of 80% casein, and 20% non-casein or whey, consisting of beta-lactoglobulin, alpha lactalbumin, bovine immunoglobulin and bovine serum albumins. Pasteurization does not denature these proteins.

Goat’s milk proteins are not a safe alternative, as they contains similar allergens to cow’s milk protein and may induce an allergic reaction in a sensitive patient. Casein-hydrolysate formulas such as Alimentum, Progestimil and Nutramigen are often recommended for use in infants with milk allergy. These formulas contain proteins that have been extensively broken down so that they are not as likely to cause an allergic reaction. Alternative, non-milk-based formulas may contain soy, however some infants may also develop soy allergy.

Where milk allergens hide:

  • Deli meat slicers can contaminate meat with cheese
  • Brands of canned tuna fish and other non-dairy products may contain casein, a milk derivative
  • Restaurant steaks may be seasoned with butter

Egg Allergy

Egg whites contain 23 glycoproteins including the major egg allergens ovomucoid, ovalbumin and ovotransferrin. Yolk is much less allergenic. Heated egg products (even baked goods) may be tolerated in small amounts, since their structure and allergenicity are altered by heat.

 Where egg allergens hide:

  • Foam or milk toppings on specialty coffee drinks. Certain cocktails may also contain egg.
  • Certain brands of egg substitutes may contain egg
  • Most commercially processed cooked pastas (including those used in prepared foods such as soup) contain egg or are processed on equipment shared with egg-containing pastas. Boxed, dry pastas are usually egg-free, but they may be processed on equipment that is also used for egg-containing products. Fresh pasta is sometimes egg-free. Read the label or ask about ingredients before eating pasta.
  • Flu vaccines contain a tiny amount of egg. Individuals with egg allergy should undergo allergy skin testing with the vaccine and if necessary be desensitized to the vaccine if the skin test is positive. [American Academy of Pediatrics (AAP) recommends that the MMR vaccine can be safely administered to all patients with egg allergy.]


Peanut is the most common food allergen for individuals over age 4. Interestingly, refined peanut oil free of peanut protein allergens is usually safe for peanut-sensitive individuals to ingest. Although once considered to be a lifelong allergy, recent studies indicate that up to 20 percent of children diagnosed with peanut allergy outgrow it.

  Where peanut allergens hide:   

  • Processed tree nuts may contain peanuts. Mandelonas may be peanuts soaked in almond flavoring.
  • Arachis oil is peanut oil.
  • African, Chinese, Indonesian, Mexican, Thai, and Vietnamese dishes often contain peanuts or are contaminated with peanuts during the preparation process.
  • Foods sold in bakeries and ice cream shops are often in contact with peanuts.
  • Many brands of sunflower seeds are produced on equipment shared with peanuts.
  • Most experts recommend that peanut-allergic patients avoid tree nuts as an extra precaution, as contamination or dual sensitivity may be an issue.
  • Peanuts can be found in many foods and candies, especially chocolate candy.


Soybeans are a major part of processed food products in the United States. Avoiding products made with soybeans can be difficult, and eliminating all those foods can result in an unbalanced diet. Studies show that most soy-allergic individuals may safely eat refined soybean oil (not cold-pressed, or extruded oil). 

Where soy allergens hide:

  • Baked goods, canned tuna, cereals, crackers, infant formulas, sauces, and soups
  • Restaurant food
  • Processed foods
  • Hamburger helper, and other food extenders
  • Vegetarian meals
  • Certain brands of peanut butter

Tree nut

Tree nut allergens (walnuts, cashews, almonds, pecans, pistachios, and hazelnuts.) cause about 0.6% of allergic reactions to foods. Patients may find that they are allergic to many nuts, not just one. However, most tree nut allergy suffers can usually tolerate peanuts, and peanut allergy patients often tolerate tree nuts. But since peanuts may be mixed with tree nuts, it is probably best to avoid all of them if you have a known nut allergy. Although tree nuts and peanuts are unrelated, occasionally patients are allergic to both.

Note: The water chestnut is not a nut; it is an edible portion of a plant root known as a “corm.” It is safe for someone who is allergic to tree nuts.
Nutmeg is obtained from the seeds of the tropical tree species Myristica fragrans. It is also safe for an individual with a tree nut allergy.

 Where tree nut allergens hide:

  • Mortadella (a type of Italian processed meat) may contain pistachios.
  • Tree nuts are used in many foods, including:
    • Barbecue sauce
    • Cereals
    • Crackers
    • Ice cream
  • Kick sacks (hacky-sacks) and bean bags are sometimes filled with crushed nut shells. (Inhaling the allergens can occur after kicking the hacky-sack.)


Fish allergy is common in children and adults, and consumption of the allergen isn’t the only cause of an allergic reaction. Fish allergy is usually a result of ingestion. However, inhalation of allergen can also cause symptoms. These allergic reactions to fish and shellfish can be severe and may result in anaphylaxis.

It should be noted that these potent allergens are not easily denatured during cooking. Fish proteins can become airborne during the cooking process, (especially boiling), and can induce an allergic reaction in sensitive individuals. There is also risk of cross-contamination in food preparation areas of a non-fish meal from a counter, spatula, cooking oil, fryer, or grill exposed to fish. It’s better to stay away from restaurants frequently serving fish and shellfish if you are highly allergic to these foods.

Q: Should iodine or iodine-based dyes used in x ray studies be avoided by a fish- or shellfish-allergic individual?

A: Allergy to iodine and/or radiocontrast material (a dye used in certain x-ray procedures), and allergy to fish or shellfish are not related. Therefore, fish and shellfish allergy are not a contraindication to the use of radiocontrast media, a common concern among radiologists.

Where fish allergens hide:

  • Caponata, a traditional sweet-and-sour Sicilian sauce, can contain anchovies
  • Caesar salad dressings and steak or Worcestershire sauce often contain anchovies
  • Surimi (imitation crabmeat)


Shellfish allergens cause frequent allergic reactions in adults. Shellfish fall into two groups: mollusks (snails, mussels, oyster, clams, squid, and octopus) and crustacea (lobster, crab, shrimp, prawns). Strong cross-reactivity exists between the two groups. Shellfish allergy is common and can be severe, leading to anaphylaxis and angioedema. 

Wheat Allergy, Intolerance and Celiac Disease

Wheat allergy (IgE-mediated) and Celiac disease (non-IgE-mediated) are two separate entitities.

Celiac disease (non-IgE-mediated) or celiac sprue, is a chronic adverse reaction to gluten. Symptoms include recurrent cramps, bloating, weight loss and bowel problems.   Those with Celiac disease will not lose their sensitivity to gluten in wheat. Therefore, lifelong elimination of gluten is necessary. 
The major grains that contain gluten are wheat, rye, oats, and barley. These grains and their byproducts must be strictly avoided by people diagnosed with Celiac disease.

Wheat-allergic individuals have an IgE-mediated response to wheat protein. This allergy is very specific and sensitive individuals must only avoid wheat, and not other gluten-containing foods. Unlike Celiac disease, most wheat-allergic children outgrow the allergy. Wheat allergy sufferers may present with hives, angioedema, GI symptoms or even anaphylaxis. Wheat can also present an occupational hazard (e.g. baker’s asthma), when flour is inhaled.

Wheat intolerance is probably more common than Celiac Disease and wheat allergy combined. Individuals do not have evidence of wheat allergy or Celiac Disease on testing but clearly get GI symptoms of bloating, abdominal pain and gassiness on ingestion of wheat containing products.

Where wheat protein allergens hide:

  • Prepared foods
  • Hot dogs
  • Certain brands of ice cream
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The allergists and asthma doctors at The Asthma Center strive to provide the best allergy, asthma, immunology, and sinus care to patients using the latest diagnostic tools and treatment strategies. Our allergists are focused on fostering strong communication with patients and improving quality of life. We have decades of medical experience treating patients, and our allergists are recognized as Top Doctors and Super Doctors. Taking care of our patients is our top priority!