Allergies Symptoms & Causes

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Here at Boston Children’s Hospital, we specialize in innovative, family-centered care. From your first visit, you’ll work with a team of professionals who are committed to supporting all of your family’s physical and psychosocial needs.

We understand that you want to learn more about your child’s allergies to keep her safe and healthy.

What is an allergy?

Allergies are overreactions of the immune system. They happen when the immune system fights harmless foreign substances called allergens, such as dust mites, pollen, pet dander and food. Therefore, treatments are usually designed to suppress the allergic reaction so your child can be safely exposed to the allergens and/or treat the symptoms when they occur.

Visible allergy symptoms are the body’s reaction to inflammatory chemicals, such as histamines, cytokines or leukotrienes. Inflammatory chemicals are released from white blood cells to fight foreign substances in the body. Each time your child sneezes, or shows some symptom of an allergic reaction, her body is reacting to the allergen. Specifically, the immune system makes immunoglobin E (IgE) antibodies to the allergens, which causes mast cells to release chemicals such as histamines, cytokines and leukotrienes to fight the allergens. Essentially, the reaction between the IgE and the allergen triggers an allergic reaction.

The process is similar for food allergies. One difference is that with a food allergy, a child is more likely to have dermatologic (skin symptoms) and gastrointestinal symptoms, such as cramps, nausea and vomiting, than with an inhalant allergy.

Signs and symptoms

What are some symptoms of an allergic reaction?

  • rhinitis: nasal stuffiness, sneezing, nasal itching, nasal discharge, itching in ears or roof of the mouth
  • allergic conjunctivitis: red, itchy, watery eyes
  • atopic dermatitis: red, itchy, dry skin
  • urticaria: hives or itchy welts
  • asthma: shortness of breath, coughing, wheezing
  • Food allergies can be life-threatening.  It is important to know the symptoms of a food allergic reaction. See our section on food allergies for signs and symptoms.


What are some allergens that may trigger an allergic reaction?

How do allergens enter the body?

  • Allergens can be breathed in through the air and enter the nose, sinuses, throat or lungs. Additionally, allergens can enter through the skin with direct physical contact or can be ingested in the case of food allergies.

Can I be genetically predisposed to allergies?

Patterns of allergies have been found in families; however, the specific genetic factors are not yet fully understood.


Q: What is the difference a regular allergy and a food allergy?

A:  Food allergy is a type of allergy in which the immune system response is essentially the same.  One difference is that a food allergy is more likely to trigger a dermatologic (skin) and gastrointestinal response, such as cramps, nausea and vomiting, than with an inhalant allergy. 

Q: How serious are most childhood allergies?

A: Childhood allergies can have a significant impact on quality of life.  Rarely, however, they can be life threatening if they’re serious and not treated, as they can affect the body’s vital functions, such as breathing.

Q: How do I know if my child needs treatment other than over-the-counter medication?

A: If the child still has symptoms even after properly taking the doctor recommended dosage of over-the-counter medications, then that would indicate they need additional treatment.

Q: What is treatment like?

A: There are several treatment options for your child’s allergies, such as immunotherapy (allergy shots),  antihistamines, decongestants, topical steroid nasal sprays and finding ways to avoid the exposure to allergens. None of these treatment options involve hospitalization or surgery.  The key to all these treatments is being vigilant about allergens that may affect your child. 

Q: Where will my child be treated?

A:Children treated through our Allergy Program receive care in our clinic.

Q: Is my child safe to eat foods with none of the allergens in the ingredients?

A: It’s important to carefully read food labels to make sure that the product is not made in a factory with an allergen, such as peanut butter, as food cross-contamination could be a problem. Even though the allergen may not be an ingredient, it could be exposed to the allergen from another product made in the factory.

Q: Can my child outgrow their allergies?

A: A study in Sweden involving allergic rhinitis (hayfever) showed that participants still had the allergy 12 years later. The results of this study suggest that sometimes children may not be able to outgrow their allergies. It should be noted that hayfever allergy is not caused by hay. It is a term that includes allergies caused by pollen from trees, grasses and weeds.

Q: Can my child develop allergies later in life?

A: Yes, allergies can develop later in life as your child may be exposed to new allergens with a change of environment such as school or work.

Q: Is there a cure for allergies?   

A: Immunotherapy can change the immune system so a child no longer has symptoms. So some patients might be “cured.” Children’s milk and peanut desensitization studies are working towards creating a cure for food allergies.

Neither Boston Children’s Hospital or the Allergy Program at Boston Children’s unreservedly endorses the information found at other websites mentioned on our Web pages.

Questions to ask your child’s doctor

After your child is diagnosed with an allergy, especially if it’s a food allergy, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you.

Lots of parents find it helpful to jot down questions as they arise; that way, when you talk to your child’s doctors you can be sure that all of your questions are concerned. If your child is old enough, you may want to suggest that she writes down what she wants to ask her health care provider too.

  • How did you arrive at this diagnosis?
  • How could allergy medicines impact my child’s life, including academic performance?
  • How may the allergy medicines interact with my child’s current medication regiments?
  • Will my child’s diet need to change while taking allergy medicines?
  • What are some things I can do to minimize my child’s exposure to allergens at home?
  • How can I provide my child with the tools to help herself when I’m not there?
  • How will the allergies impact their adult life?
  • How should I talk to my child about her allergies?
  • What support services are available to help educate my child about their allergies?
  • What are some steps I should take if my child suffers from a severe allergic reaction?

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Food allergy falsehoods

Lynda Schneider, MD, director of Children’s Hospital Boston’s Allergy Program, dispels common misconceptions about food allergies.


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