Food Allergy in children: What are the common symptoms?

Food allergy is an abnormal immunologically mediated response of the body after eating a certain food. Even a very tiny amount of the allergy-causing food can trigger signs and symptoms in a child.

How common is food allergy in children?

Food allergy is estimated to affect 6-8 % children less than 3 years and up to 3-4 % adults.

What are the common symptoms of food allergy in children?

Symptoms of food allergy in children begin within a few minutes to two hours after eating the food to which the child is allergic. In some children the allergic reaction is mild but for few food allergy reaction can be severe and even life-threatening called as Anaphylaxis. The most common symptoms of food allergy in children:

  • Tingling or itching in the mouth
  • Hives or urticaria
  • Swelling of the lips, face, tongue and throat or other parts of the body (also called as Angioedema)
  • Nasal congestion or runny nose, difficulty in breathing, chest congestion or wheezing
  • Tummy pain, cramps, loose motions, nausea or vomiting
  • Dizziness, light headedness or fainting

Food allergy sometimes confused with food intolerance. While more common and bothersome, food intolerance is a less serious condition that is not mediated through our immune system.

Food Allergy in children: What are the common foods?

While any food can cause an adverse reaction in children, more than 90 percent of food allergy reactions are caused by eight types of food.
These eight foods include: Eggs, Milk, Peanuts, Tree nuts, Fish, Shellfish, Wheat and Soy Certain seeds, including sesame and mustard seed, also are common food allergy triggers and considered an important allergen in few countries.

Milk Allergy

Milk allergy is the most common food allergy in children. It is estimated to affect 2–3% children younger than 3 years of age. Children are allergic to the milk protein. Milk allergy is typically discovered very early in age usually when the child is given formula feed. Occasionally, milk allergy can be seen in breast-fed babies if the mother is  consuming cow's milk as small amount of cow’s milk protein also comes out in her breast milk. Avoidance of milk and milk products is recommended. Many children outgrow milk allergy but in some children it persists for lifetime.

Egg Allergy

The second most common food allergy after milk is allergy to eggs. Most children with egg allergy are allergic to egg white protein but some children are allergic to egg yolk protein. Most kids outgrow this food allergy by age 5 years of age.

Peanut Allergy

Peanut allergy is one of the most common causes of severe food allergy in children. Peanut allergy can lead to  life-threatening allergy reactions also called as anaphylaxis. For some children with peanut allergy, even very small amounts of peanut can cause very serious reactions. Mostly, peanut allergy persists for life.

Tree nuts Allergy

Almond, cashew nut, pistachios and walnut are the most commonly consumed tree nuts. The lesser known include pine nut, lichee nut, brazil nuts, chestnuts, hazelnuts, macadamia nuts and pecans. Nut allergy is usually a lifelong food allergy.

Fish Allergy

The primary allergen responsible for a fish allergy is a protein known as parvalbumin. Parvalbumins vary little between different fish species, hence food allergy to one fish usually results in an food allergy to other fishes. Parvalbumins are extremely heat resistant and hence cooking does not render fish non allergic. Fish allergy does not predispose to food allergy to shellfish.

Shellfish Allergy

The allergen responsible for shellfish allergy is known as tropomyosin, which entirely different from parvalbumin in fish. Marine animals in the shellfish category include:

  • Crustaceans include crabs, lobster, crayfish, shrimp and prawn.
  • Mollusks include squid, snails, clams, oysters and scallops.

Some people have food allergy to only one type of shellfish but can eat other types of shellfish. Other people with shellfish food allergy are allergic to all shellfish.

Wheat Allergy

Wheat allergy is a food allergy reaction to foods containing wheat. This condition is different from celiac disease in which an abnormal immune reaction occurs to gluten. Since wheat is present in many foods, avoiding wheat is not very easy.

Soy Allergy

Soy is a product of soybean, is a common food allergy in children. Soy allergy starts in early infancy with reaction to soy-based infant formula. Most children with soy food allergy outgrow symptoms by 5 years although in some children soy allergy can persist. Kids with soy food allergy have to avoid multiple foods which contain soy like breakfast cereals, chocolate, bakery goods and certain meat products.

Food Allergy in children: How do we diagnose?

With the help of a paediatric allergist, you can know what food allergens are causing symptoms in your child. This would require some allergy testing. Allergy testing for food allergy can be done in two ways as detailed below:

  • Skin allergy test or Skin Prick Test (SPT): in this test a small amount of allergen is put on the forearm of the child and gently scratched with a special lancet. This leads to a wheal and flare response which is read after 15 to 20 minutes. The test is painless and bloodless. Skin test gives accurate results in 20 minutes. Many allergens can be tested simultaneously. In addition any food can be tested to which a child is deemed allergic to. In this test we will prick a piece of the food with a lancet and then scratch your child’s skin with it. This is called as a prick-to-prick test.
  • Blood allergy test  (Also called as ImmunoCap or Serum Specific IgE): The new generation blood tests are very reliable and are used often. The results take a few days to be available (usually 7-10 days). They are usually more costly compared to skin tests.

Food Allergy in children: How to Manage?

The best way to manage a food allergy is to avoid giving that particular food to your child that causes problems.
Some children with complex food allergy would require expert help from a dietician.

Food Allergy in children: When do you need to see a Pediatric Allergist for your child’s allergies?

You need to see a Pediatric Allergist for your child if your child is getting food allergy symptoms shortly after eating a particular food. Seek emergency medical care if your child is getting any signs or symptoms of anaphylaxis, such as:

  • A. AIRWAY: persistent cough, hoarse voice, difficulty swallowing, swollen tongue
  • B. BREATHING: turning blue, difficult or noisy breathing, wheeze or persistent cough
  • C. CONSCIOUSNESS: Persistent dizziness, pale or floppy, suddenly sleepy, collapse/unconscious

There can be additional symptoms like vomiting, abdominal pain and diarrhea.