Food Allergy-Causes, Symptoms, and Treatments

food allergy

Food Allergy

Food allergy is simply when your body immune system reacts to certain foods seeing it as being harmful to your body whereas the food isn’t harmful. The symptoms of food allergy are mostly found in young children and babies and could surface within minutes to several hours of the exposure.

A report by the Centers for Disease Control and Prevention deduced that about 4% of adults and 4%-6% of children are mostly affected with some kind of food allergy at a given time. Also, about 50 million Americans do experience several kinds of allergy. Foods that cause these allergic reactions are known as allergens. You can have an allergic reaction in foods you have eaten for several years without problems.

Causes of a Food Allergy

Several foods are known to make you develop food allergy rapidly. People with a previous family background of allergies could result in a child developing food allergy towards those foods. It could also be common in regions where those foods are mostly consumed like in Asia; most children there are allergic to rice. Below are the most common foods:

Fish and shellfish

Tree nuts and peanuts

Soy milk and cow’s milk



Rice and wheat

Some foods tend to cause allergic reactions in adults like fish, shellfish, tree nuts, peanuts, fruits, and vegetable pollen.

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Food Allergy Signs and Symptoms

 Symptoms of food allergy may begin as mild to a more severe symptom. Most at times the symptoms may begin immediately or in an hour time. Its symptoms include the following:



A mild headache

Having a harsh voice

Swelling of the tongue, lips, and eyelid

Continuous coughing


Experiencing low blood pressure

Itching of the mouth, tongue, skin, eyes, and other parts of the body



A runny nose


Feeling dizzy

A situation where the allergic reaction arises from symptoms affecting the circulation of blood and respiratory tract is referred to as anaphylaxis. Anaphylaxis can be a life-threatening reaction which affects breathing making your body experience shock; reactions may be happening at the same time with other parts of the body (for instance, a swelling mouth accompanied by a stomachache).

 Also, anaphylaxis affects mainly people who are allergic to seafood, peanuts, and even asthmatic patients. An anaphylactic shock occurs when the symptoms are associated with a decrease in blood pressure.

Categories of Food Allergies

A category of any food allergy may include the following three, namely:

  • Immunoglobulin E (IgE) Mediated: This is the most prevalent type and may surface shortly after consumption and it involves anaphylaxis. Here, the IgE antibodies tend to react with a particular food.
  •  Non-IgE Mediated: It involves only some other parts of the body’s immune system which reacts to a particular food. This reaction might cause complications in diagnosis since it does surfaces some hours after you must have been done eating.
  •  IgE and/or Non-IgE Mediated: This involves a hybrid of the two types above.

IgE Mediated Food Allergies

This type of food allergy is predominant in children and young infants and they include; milk, egg, tree nuts, peanuts, wheat, and soy. Its allergic reaction may involve your mouth, skin, eyes, gut, heart, lungs, and brain. Below are the most common symptoms:

Stomach pain, vomiting, and diarrhea

Having awful feelings

Hives, skin rash and itching

Shortness of breath, difficulty breathing, and wheezing

Swelling of the lips, throat or tongue

Never take the allergic symptoms for granted. These mild and severe symptoms can result in a serious allergic reaction known as anaphylaxis. Since this reaction involves several parts of the body, it could get worse rapidly. It is best recommended to treat anaphylaxis with epinephrine instead of antihistamines for optimum result.

Cross-Reactivity/Oral Allergy Syndrome

A person allergic to a particular food may have a reaction to other related foods. For example, you might be allergic to crab and that will also lead to you experiencing the same thing with lobster and shrimp. Someone allergic to walnuts may react to cashew nut, peanuts, pecans, and almond nuts. The reaction between these different foods is referred to as cross-reactivity. Cross-reactivity does occur when proteins in one food are similar to the protein in other food. It can also be common between latex and particular food. For instance, a young infant who is allergic to latex may also experience an allergy to avocados, bananas, and chestnuts.

Furthermore, oral allergy syndrome may occur in a situation where proteins in the pollens are mistaken to be protein similar in several vegetables and fruits. You can see your child who is allergic to ragweed exhibits similar allergic reactions to bananas and melons.

Finally, itching of the mouth, tongue or throat, vomiting, hives at the back, shortness of breath are the commonest symptoms of oral allergy syndrome. It should not be taken for granted because it could be life-threatening in rare cases.

Read Also: Food Poisoning: Signs, Symptoms, Causes, Treatment,and Prevention

Non-IgE Mediated Food Allergies

Most of its symptoms occur in the digestive tract and may include excessive diarrhea and vomiting. Although its symptoms take longer to surface and can last longer than IgE mediated allergy symptoms. Non-IgE mediated food allergy doesn’t require epinephrine for its treatment instead it’s best to refrain from any food that causes the reaction. The following conditions best explain non-IgE mediated food allergies:

Note that not all young infants who react to a particular food definitely have an allergy, they may experience food intolerance like gluten intolerance, lactose intolerance, and dye sensitivity/sulfite sensitivity. Either you refrain from the foods that cause the reaction or you consult your medical allergist to properly diagnose whether your child has an IgE food allergy or non-IgE food allergy. In some rare cases, a child might even have both IgE and non-IgE food allergy.

Eosinophilic Esophagitis (EoE)

This is simply inflammation of the esophagus as a result of an allergy to food consumed. A person with eosinophilic esophagitis tends to find it difficult and felt pains in the course of swallowing food. Taking of medications or placing the patient on a special diet is the major ways in treating EoE. Its symptoms may range from stomach ache, loss of weight, reflux, chest pain, irritability, vomiting, and feelings of food being stuck in their throat. Also, the symptoms may surface for days or better still weeks after consuming a food allergen.

Food Protein-Induced Enterocolitis Syndrome (FPIES)     

Food protein-induced enterocolitis syndrome (FPIES) another form of delayed food allergy reaction stems which is a severe gastrointestinal reaction that mainly occurs between 2-6 hours after feeding on soy, milk, particular grains and some other foods which are in solid form. It is found mainly in young infants on exposure to these foods for the first time or during the process of weaning. FPIES do involve continuous vomiting giving rise to dehydration and sometimes the baby might experience bloody diarrhea. This is because the symptoms look like that of a bacterial infection or viral illness. Also, a patient with FPIES should undergo treatment of intravenous rehydration to be whole again.

Allergic Proctocolitis

This allergy is due to breast milk or formula. Allergic proctocolitis affects infants usually in their first year of life and ends after a year. It involves inflammation of the lower part of the infant’s intestine.

Watery stools, green stools, anemia, diarrhea, blood-streaked stools/stools filled with mucus and continuous vomiting are its main symptoms. A child can be free from allergic proctocolitis by not eating those foods that cause the reaction in his or her diet and going for proper medical diagnosis if you notice the above symptoms.

Diagnosis of Food Allergy

Diagnosis of food allergy is mainly done using an elimination diet, medical history, skin tests, and blood tests for food-specific immunoglobulin E antibodies or oral food challenge. Although one can develop a food allergy at any age it is predominant in a child early life. Consult a food allergist if your child is experiencing any of the above symptoms and he will ask about any previous family background of the allergy thereby knowing which suitable test you might carry out for effective diagnosis.  

Most at times, an allergist may ask the following questions to ascertain your symptoms before diagnosis:

  • What and how much of the food you consume?
  •  When did you start experiencing the symptoms?
  •  What are the symptoms like and how long did they last?

After knowing your medical history, your allergist will now demand you carry out some blood/skin tests to ascertain whether food-specify immunoglobulin E antibodies are found in your body.

Skin-Prick Tests

This is usually performed on the skin either on the back or arm of an individual using a sterile protruding needle to ascertain whether a person is positive or negative to the allergen for optimum diagnosis. Here the food allergen which is usually in a liquid form is being placed on the little hole that has been pricked at your back. It does involve both a control and a test; an individual is confirmed positive if there is a reaction between the allergen and your skin which appears in the form of bumps from a mosquito bite. The control will be checked if there is a reaction of your skin to a liquid without the allergen and the two results will be compared. Skin-prick test result is always available in at most 25 minutes.

Blood Tests

In blood tests, its result is more reliable than skin test despite taking a long time for the result to be out usually in a week. This determines the amount of IgE antibody against the particular foods that are being tested.

Your medical allergist gets these results to know proper diagnosis suitable for you. Having a positive result doesn’t actually mean you have an allergy but a negative result could be important in striking one out.    

Also, in some instances, a food challenge will be performed under diligent medical supervision; the patient will be given a little amount of the triggering food in increasing concentrations over a particular period of time. This is then accompanied with few hours of observation to check for the occurrence of the reaction.

Food Challenge Test

This food challenge test is useful where a patient history is uncertain or the blood/skin tests are not ascertained to know if the allergy has been outgrown for long. Since this test is very delicate it is usually performed by highly skilled allergists at a standard food challenge center or in a doctor’s office and emergency medication/equipment on standby.          

Differential Diagnosis of Food Allergy

The following are the main differential diagnosis of food allergies:

Celiac Disease

Since it arises from a permanent intolerance to gluten (which is a substance found in wheat and flour that holds dough firmly together), it is not regarded as an allergy or intolerance but a more severe, multiple-organ autoimmune disorder which affects mainly the small intestine.

Hereditary Angioedema

Here the angioedema is mainly attacked giving rise to irregular diarrhea and abdominal pain.

Lactose Intolerance

Lactose intolerance arises as a result of insufficient lactase and not an allergy and is mainly found among non-westerners. Young patients are at risk with this disease in severe cases and it generally develops later in the future.

Read Also: Skin Conditions Associated With Food Allergies

Irritable Bowel Syndrome (IBS)

This is simply a disorder involving the large intestine and mainly leads to pains in the stomach, a lot of gas, constipation, and diarrhea. IBS has four types namely:

  • IBS involving constipation (IBS-C)
  •  IBS involving diarrhea (IBS-D)
  •  Mixed IBS (IBS-M)
  •  Unsubtyped IBS (IBS-U)

Food Allergy Treatment/Management

The best method in treating a food allergy is to abstain from foods that may cause you problems. Carefully read labels to know the actual ingredients of the food products and see if you are allergic to any of the ingredients and avoid consuming the products.

Also, the Food Allergy Labeling and Consumer Protection Act of 2004 (FALCPA) required manufacturers of packaged foods that are produced in the United States identify in a simple, clear language, the appearance of any of the eight (8) most predominant food allergens-wheat, tree nut, milk, fish, egg, soy, crustacean shellfish, and peanut in any of their products.

Some food products are not bound by law in the case of those labeled with precautionary statements like “might contain”, “may contain”, and “made in a shared facility” and consult your allergist before consuming any of those foods. Also, be warned that Food Allergy Labeling and Consumer Protection Act of 2004 (FALCPA) is not applicable to the U.S. Department of Agriculture (poultry, meat, and some specific egg products) and those that are regulated by the Alcohol and Tobacco Tax and Trade Bureau which involves beer, distilled spirits, and wine. The law isn’t applicable to shampoos, cosmetics, and other health and beauty aids, in which extracts of tree nuts or wheat proteins may be present in some of these products.     

Eating Out in a Restaurant       

Avoid eating outside in a restaurant and if you are to eat make sure you have observed that the workers are neat and they are observing good manufacturing processes. You can request o see the chef and inquire about available dishes that are not in contact with any allergens/the several ingredients used in preparing any of the food you are to eat and stress that you are allergic to some certain foods for your optimal safety.


Anaphylaxis should not be taken for granted because food allergy is the main cause of it to a large population in the U.S. outside the hospital setting. Epinephrine shouldn’t be far away from patients with anaphylaxis so as to be on the safer side and you should be taught on how to use it by your allergist. Make sure you always check the expiring date of your epinephrine auto-injector and ask for prescription renewals from your licensed pharmacy. 

 Also, know that epinephrine has some few side effects like feeling dizzy, feeling of anxiety, shivering and restlessness. In rare cases, you can develop a quick rise in your blood pressure and buildup of fluids in the lungs, abnormal heartbeat, and heart attack.

In the case of food allergies among young infants in school, the school should have trained allergist personnel to care for any child with a food allergy and must have drafted emergency action plan in place. Care should be taken when administering the epinephrine with the auto-injector so as not to endanger the child.

Use of Antihistamines

Antihistamine is used in treating allergic reactions involving mild symptoms. It works by blocking the action of histamine which makes your blood vessels to open up and become open to plasma proteins. Diphenhydramine is the most common antihistamine used in treating some food allergies. You might experience some side effects like itchy body feelings and dizziness.  

Prevention of Food Allergy

Exclusive breastfeeding for more than four (4) months may help avert a child from contracting atopic dermatitis, wheezing, and cow’s milk allergy.

Also, early exposure to potential allergens may help immensely.

Avoid complete abstinence from foods you know you might be allergic to be on a safer side and refrain from kissing, participation in sports, skin contact, cosmetics, alcohol, and blood transfusion because of hypersensitive reactions.  

Care should be taken in the aspect of not inhaling allergens on exposure to atmosphere especially for people working in the food industry. Notwithstanding, this can also take place at home, inside an airplane, and restaurants.

Read Also: 19 Health Benefits of Banana to the Body

Food Allergy Treatment Center in the USA

Adult Allergy Treatment Programs: National Jewish Health

Allergy and Immunology Research: John Hopkins Children’s Center

Allergy Treatment Center of New Jersey, P.C. 

Food Allergy Center, Massachusetts General Hospital, Boston, MA

Food Allergy Treatment Center, Alabama

Food Allergy Treatment Boise/Oral Immunotherapy OIT

Food Allergy Treatment: Food Allergy Center of Florida

Food Allergy Program, Boston Children’s Hospital

Jaffe Food Allergy Institute, Icahn School of Medicine

New England Food Allergy Treatment Center, 836 Farmington Avenue, West Hartford, Connecticut, USA

Oral Immunotherapy for Food Allergy, Kansas City

Southern California Food Allergy Institute  

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