Everything you need to know about food allergy

Nearly 1-10 percent of the population, especially young children suffer from food allergies. Nearly 3.5 percent of the US population is suffering from food allergy.

At the 6 months of age we need to start the complementary feeding to babies along with breastfeed. This is the time infants are first introduced to the food items.

As a parent you may detect some children suffering and some children losing weight at this time and one of the important causes for this can be food allergy along with wrong complementary feeding practices.

Everything you need to know about food allergy
500Everything you need to know about food allergy

What are the symptoms of the food allergy?

The manifestations of the food allergy can be mild to moderate and have a variety of manifestations. The manifestations may depend upon the involving organ system.

So let us see how food allergy can manifest in your children or even in adults:

Cutaneous manifestations of food allergy

Early manifestations of food allergy include symptoms of skin like pruritus that is itching of skin and redness and insect bite like macules on skin. There may be marks of excoriation if the patient has tried to scratch the area where symptoms come. Sometimes there may be an appearance of measles like rash on the skin. If it occurs repeatedly, the dry and hard scales may be developed on the skin.

Eye manifestations

Food allergy may cause itching of eyes. The conjunctiva of the eyes may appear red. Eyes may have watery discharge or tears. The pupils and area around the eyes may swell in this condition. These manifestations may occur within a few hours of food intake.

Upper respiratory tract

Food allergy may cause upper respiratory tract infections. They are stuffy or congested nose, running nose, sneezing, and itching sensations in nose and throat with throat pain, changed voice like hoarseness and dry cough. Extreme conditions like swelling of larynx which may block the windpipe that may be life threatening.

Lower respiratory tract

Food allergy may cause lower respiratory tract symptoms like difficulty in breathing and wheezing that whistle like the sound a person breaths. Cough and feeling of tightness in chest. You may see skin between the ribs sagging in the chest when a person breaths. These symptoms are all similar to asthma. They can appear within a few minutes to hours after having food.

Oral symptoms

These symptoms may occur because of food allergy and they appear around or inside the mouth. They include itching and swelling of lips and palate, tongue. It may cause difficulty in eating and breathing also affects respiratory tract.

Other digestive tract manifestations of food allergy

Feeling of nausea, abdominal pain and vomiting, diarrhea. In some children it may cause blood in stool which may be frightening for the parents. In some children there may be irritability and refusal to food and also after some days may cause loss of weight or failure to gain weight.

Cardiological (heart) manifestations of food allergy

In some children food allergy may cause increased or decreased heart rate with decreased blood pressure. This decreased blood pressure may cause fainting and dizziness. This condition is anaphylaxis. If not managed immediately may cause death.

Which food can cause food allergy?

Any food can cause allergy to a person who has that tendency of allergies. The most common foods that cause allergy are as follows:

Hen’s egg white

Everything you need to know about food allergy
Hen’s egg white

This type of food allergy usually starts at age 0-1 year of life and children with this allergy may be allergic to other bird eggs too. Most of the children suffering from these allergies outgrow the condition till 7 years of age.

Cow milk

Everything you need to know about food allergy
Cow milk can cause allergy

The first manifestations of the cow milk allergy are detected in 0-1 year age and they may have allergies to other milks like buffalo, goat milk and sheep’s milk.


Everything you need to know about food allergy
500Peanuts can cause allergy

First time manifestations of the peanuts allergy usually appear at age 1-2 years of age. These children may be allergic to other legumes and lentils and peas and nuts.


Food allergy to fish may be detected in old children and adults. Those with these allergies may be allergic to other fishes and shellfish.

Wheat allergy

Wheat allergy symptoms may come for the first time in children aged 6-24 months. These children may show allergic manifestations to other grains which contain glutens like rye and barley.


Soybean is consumed for its rich protein content. Children who have allergy to these soybeans may have symptoms for the first time in the first two years of their life. They may have allergic symptoms after consumption of other legumes.

Apple, carrots and peaches

Allergies to these fruits and nuts are usually first detected in late childhood and adults. These adults may show allergies to other fruits and nuts. Usually fresh fruits eaten raw may show allergies but they are non reactive to cooked apples and fruits.


This allergy to kiwi can be detected at any age. Those with allergies kiwi may be allergic to bananas and avocado. 

How to prevent food allergy?

Following are the simple ways which help to reduce the incidences of the food allergies in children.

Exclusive breastfeeding

Breastfeeding is the best food  for babies. We have already explained the benefits of breastfeeding in an earlier post. Exclusive breastfeeding for the first 6 months of the life protects infants and children from developing food allergies in future.

Complementary food

Complementary food should be started to infants at 6 months of age. Starting complementary food at 6 months of age after giving exclusive breastfeeding for the first 6 months of life reduces the chances of food allergy.

Introduce single food at a time

In complementary feeding infants should be introduced to single food at the time. Initially low risk food is introduced. Like if you are introducing rice, give the food made up of only rice for 4 days then introduce other pulses one by one.

High risk foods

Introduce potentially highly allergenic foods (fish, eggs, peanut products, milk, wheat) soon after the lower-risk foods (no need to avoid or delay)

Don’t avoid allergenic foods during pregnancy or nursing.

Soy-based formula

There is a myth that soy based formulas prevent allergic disease which is not true. Soy-based formulas do not prevent allergic disease.

How to diagnose food allergy?

Knowledge of the symptoms helps to diagnose the food allergy. A thorough history is needed to diagnose this condition. 

The parent who daily feeds the child should accompany the child to the doctor to give the detailed history about diet and the symptoms.

Additionally you should carry the relevant medical history file if any to see the previous record of treatment and growth of the child.

History and physical examination for food allergy

The goal of detailed history are to establish facts about:


The history can suggest the food which can provoke the allergic reaction and how much quantity of food was ingested before the symptoms.


The history about diet also helps to find out the interval between ingestion of the provoking food and appearance of the symptoms.


The history taking helps to find out the types of symptoms and their severity.


Whether there were similar episodes of symptoms with similar food in the past. How frequently it has occurred in the past.

Lab tests

Lab tests can be used to identify provoking agents which can induce the symptoms in the patients. These lab tests mainly detect the IgE antibody mediated allergic reactions to the food.

Prick test

Prick test is useful to detect the allergy to specific food if known in history as a provoking agent.

The produce from the fresh fruits are useful for this test as readymade preparation may alter the antigens from the fruits.

In this test the fruit product is injected in a small amount on skin and the response is observed for a few minutes.

Negative test virtually excludes the possibility of the reactivity or allergy to that food.

Positive test does not indicate that the patient has a confirmed allergy to that food. The patients who test positive on tests may not be allergic to food when ingesting that food.

So rather than confirming, the prick test is for excluding the allergy to the food.

Further confirmation with specific IgE antibody tests is useful. Quantitative IgE levels are useful to detect the allergy.

IgE levels

  • Serum food-specific IgE levels ≥15 kUA/L for milk (≥5 kUA/L for children ≤1 yr)
  • ≥7 kUA/L for egg (≥2 kUA/L for children <2 yr)
  • ≥14 kUA/L for peanuts are associated with a >95% likelihood of clinical reactivity to these foods in children with suspected reactivity.

Food elimination and challenge test

Above tests are not helpful for the cell mediated food allergies and other reactions. So eliminating a suspected group of food for a period and then introducing that food to see whether symptoms reappear is the only practical test to assess whether the patient is allergic to a food.

These tests are performed by allergy specialists who have skill to manage anaphylaxis. Before a challenge test, stop the food for 14 days to 8 weeks depending on the type of allergic reaction suspected and then introduce it under observation.

What is treatment for food allergy?

Identifying and then eliminating the food to which a child is allergic is the only approach to treat the food allergy.

Some common items are difficult to eliminate like grains and eggs and peanuts. 

Moreover most of the children with food allergy outgrow the condition in a few years. Evaluate the child periodically to know when to introduce the eliminated food.

Combination of oral immunotherapy with an anti IgE antibody like omalizumab seems promising in research. 

Most children with cow milk and egg allergy are not allergic to extensively cooked milk and eggs. Continue these items cooked extensively. Continuing them makes the resolution process faster.

<span class="has-inline-color has-luminous-vivid-orange-color">Dr Yatin Bhole MBBS DCh DNB</span>
Dr Yatin Bhole MBBS DCh DNB

This article was written by Dr Yatin Bhole who is practicing Pediatrician at Bhole Children Clinic, Ravet. This post is for general information and before applying it on yourself, you should meet your doctor or meet us in person.

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