Food Allergies in Children

What Is a Food Allergy?

The function of the body’s immune system is to fight off infections and other dangers to keep us healthy. If the immune system senses that a food or a substance in a food is a danger to the body, it may trigger an allergic reaction. This is different from a food intolerance, which does not involve the immune system.

Food allergies are divided into two main types: Immunoglobulin E (igE)-mediated and non-IgE-mediated.

IgE-Mediated Food Allergies

IgE-mediated food allergies occur quickly, usually within a few minutes to a few hours of ingestion of the food. In IgE-mediated food allergies, the immune system sends IgE antibodies into the bloodstream, which causes the body to release histamine and other substances into the bloodstream. Histamine causes symptoms such as coughing, wheezing and hives.

Non-IgE-Mediated Food Allergies

A non-IgE-mediated food allergy is caused by a reaction involving other components of the immune system besides IgE antibodies. Symptoms of this type of allergy typically take significantly longer to develop than those of IgE-mediated food allergies, sometimes up to several days. Non-IgE-mediated food allergies, which present with symptoms of variable severity and affect the gastrointestinal tract in response to specific dietary triggers, include the following:

What Causes Food Allergies?

Most IgE-mediated food allergies are caused by the following foods:

• Milk
• Egg
• Soy
• Wheat
• Sesame
• Peanut
• Tree nuts
• Fish
• Shellfish

The most common foods that trigger non-IgE-mediated food allergies are cow’s milk and soy proteins in infants and wheat in older children.

Signs & Symptoms of IgE-Mediated Food Allergies

Food allergies can produce symptoms in multiple areas of the body. Common signs and symptoms of IgE-mediated food allergies include:

• Skin: hives (red, itchy blotches or welts) and mild to severe swelling
• Nose: clear discharge, itch, congestion
• Eyes: redness, itching, tearing
• Mouth: itching, lip swelling, tongue swelling
• Throat: tightness, trouble speaking, trouble inhaling
• Lungs: shortness of breath, cough, wheeze, rapid breathing
• Stomach: nausea, repeated vomiting, abdominal pain, diarrhea
• Brain: anxiety, agitation, loss of consciousness
• Heart and circulation: weak pulse, loss of consciousness

It is important to note that IgE-Mediated food allergies can trigger anaphylaxis, a severe, life-threatening reaction to an allergen. Anaphylaxis is a medical emergency. Call 9-1-1 if you think your child has anaphylaxis. The reaction is usually treated with an injection of epinephrine. As such, you should carry an emergency kit with self-injecting epinephrine if your child is at risk for anaphylaxis. If you have emergency injectable epinephrine, use it before you call 9-1-1.

Unlike IgE-mediated food allergies, non-IgE-mediated food allergies are very rarely life threatening because they do not cause anaphylaxis. Symptoms of non-IgE-mediated food allergies can be similar to those of IgE-mediated food allergies and include:

• Red and itchy skin, without a raised, itchy red rash (hives)
• itchy, red, dry and cracked skin (atopic eczema)

Other symptoms of non-IgE-mediated food allergies can be much less obvious and mistakenly attributed to causes other than the food allergy. These symptoms include:

• Vomiting (with or without diarrhea)
• Abdominal cramps
• Constipation
• Excessive and inconsolable crying in babies even though the baby is well-fed and doesn’t need a diaper change

How Are Food Allergies Diagnosed?

Diagnosis of your child’s food allergy can occur in a few ways:

• Your child may have a reaction to a food that leads directly to an evaluation by a pediatric allergist
• Your child may have a flare of eczema, causing concerns about the possibility of a food allergy
• You may have discussed concerns about your child with their pediatrician, who recommended consultation with a pediatric allergist or immunologist

If your child sees a pediatric allergist at UH Rainbow Babies & Children’s, we will take a detailed look at his or her health history and your family health history. We will also perform a thorough physical exam. Based on our assessment, our allergy specialists may recommend testing for suspected IgE-mediated food allergies, including one or more of the following tests:

• Oral food challenge test: At our Food Challenge Clinic, we give your child the suspected trigger food in a controlled setting, starting in small doses and slowly increasing the dose, monitoring his or her possible reaction or not to the food. This medically supervised test is also helpful in determining if your child has outgrown an already identified food allergy.
• Skin test: Skin testing involves introducing a small quantity of the specific food on your child’s skin, usually on the forearms or the back, depending on their age.
• Blood test: A blood test called allergen-specific IgE testing measures the level of antibodies produced in the blood in response to a food allergen.

Regarding non-IgE-mediated food allergies, we do not yet have useful blood or skin allergy tests. Diagnosis of non-IgE-mediated food allergies is established by removal of the suspected food or foods and conducting food challenge testing. When a diagnosis is reached, the main step in treatment is avoidance of the trigger food. We may choose to perform another food challenge test within a year to see if the condition has resolved.

How Are Food Allergies Treated?

IgE-Mediated Food Allergies

IgE-mediated food allergies can occur quickly. Whenever more than one body system is involved in a food reaction (for example, the throat and skin), the best treatment available is epinephrine. Epinephrine is available in a number of forms, including auto-injectors such as Epi-Pen, Auvi-Q and other generic types.

If your child’s reaction is initially mild and you’ve given him or her an antihistamine but the reaction worsens rapidly, you should give them epinephrine. Kids with IgE-mediated food allergies should always carry epinephrine with them or have it readily available for them at places where they routinely spend time, such as daycare, school and home.

Non-IgE-Mediated Food Allergies

The primary treatment for non-IgE-mediated food allergies is avoidance of the allergy-producing food. Because non-IgE-mediated food allergies are generally non-life-threatening, epinephrine is not used to treat them.

When to Call 9-1-1

If your child has a severe allergic reaction to a food, you should call 9-1-1 and/or go to the emergency department regardless of whether you give him or her epinephrine. Epinephrine works well but wears off quickly. As such, your child’s condition should be evaluated by a trained medical professional.

If the reaction gets worse, your child may need other medicines, including:

• A second dose of epinephrine
• Antihistamines such as cetirizine, famotidine or diphenhydramine
• Albuterol or a similar bronchodilator inhaler used to treat breathing issues
• Steroids
• Oxygen