What is an allergy?
The immune system protects us by attacking harmful substances such as viruses and bacteria. An allergy is the immune system’s response to a substance called an allergen.
The allergen is not harmful for most people. However, when a child has an allergy, the immune system treats the allergen as an invader and over-reacts to it. This results in symptoms from mild discomfort to severe distress.
Allergic disorders, including food allergies, are common in childhood. Many children with allergies also have asthma.
Types of allergens
Common food allergens
Food allergens can also be hidden in common party dishes such as cookies, cakes, candies or other foods. Always ask the cook or the host if dishes contain foods your child is allergic to.
Far more people have a food intolerance than a food allergy. Unlike a food allergy, a food intolerance does not involve an immune reaction. Rather, it produces unpleasant symptoms as food is digested. These symptoms appear over a few hours rather than as soon as the food is swallowed or inhaled.
Common airborne allergens
Dust mites are common airborne allergens. These tiny bugs live in warm, damp, dusty places in your home and survive by eating dead skin cells. Their waste is a major cause of allergies and asthma.
Other common airborne allergens include:
- pollen from trees, weeds and other plants
- mould
- pet dander (dead skin cells from pets)
- cockroaches
Other common allergens
- Insect bites or stings
- Medicines
Signs and symptoms of allergies
Allergic reactions will vary from child to child and from allergen to allergen. Where you live can also affect the type and severity of the allergy.
Symptoms for food allergens and insect bites or stings
Your child’s response to a food allergy or insect bite will depend on how sensitive they are to that food or bug. Symptoms can include:
- itchy mouth and throat when food is swallowed
- skin rashes, such as hives (raised, red, itchy bumps)
- sneezing
- itchy, runny or stuffy nose
- conjunctivitis (red, swollen eyes) or itchy, watery eyes
Symptoms for airborne allergens
Common symptoms with airborne allergens may include:
- sneezing
- itchy nose or throat
- stuffy or runny nose
- red, itchy and/or watery eyes
- headaches or plugged ears
Symptoms of severe allergic reactions
Anaphylaxis is the most severe type of allergic reaction. Even exposure to small amounts of allergens can trigger anaphylaxis in some allergic children.
The signs and symptoms of anaphylaxis may include sudden onset of:
- hives, itching, redness of the skin
- swollen eyes, lips, tongue or face
- difficulty breathing, tightness of the throat or difficulty swallowing
- abdominal (belly) pain, nausea, vomiting or sudden onset of diarrhea
- coughing
- stuffy and/or runny nose, watery eyes, sneezing
- fainting, confusion, lightheadedness or dizziness
- rapid or irregular heartbeats
- cold, clammy, sweaty skin
- voice changes
Anaphylaxis is a medical emergency and requires immediate medical care. Give epinephrine (if available) and call an ambulance.
What causes an allergic reaction?
Allergens may come in contact with the skin or be breathed in, eaten or injected.
When the body detects an allergen, it sends a signal to the immune system to produce antibodies called immunoglobulin E (IgE). Those antibodies cause certain cells in the body to release chemicals called histamines. Histamines travel through the bloodstream to fight the invading substance or allergen.
Your child’s allergic reaction depends on which part of their body has been exposed to the allergen. Most commonly, allergic reactions affect the eyes, inside of the nose, throat, lungs or skin.
What your child's doctor can do for allergies
If you suspect your child has an allergy, they should see an allergist. This is a doctor who specializes in diagnosing and treating allergies.
To identify your child's allergy, the allergist will usually:
- examine your child
- ask for your child’s allergy history
- ask for a description of your child’s allergic symptoms
Your child might then have skin tests, blood tests, a chest X-ray, a lung function test or an exercise tolerance test. The allergist will explain these tests to you.
When the tests are done, the allergist will use the results to make a diagnosis. You and your child will meet the allergist at a later date to discuss them.
How to prepare for an allergy test
Your child may need to stop using certain medications for a period of time before an allergy test. These medications may include antihistamines. Always ask your doctor if your child should stop taking medications before the visit.
How to prevent allergic reactions
Food allergens
Your child must avoid all foods they are allergic to. Some children may outgrow their allergies, but others may have to avoid the allergen for life.
Avoiding a food allergen can be difficult. As a result, many children unintentionally eat food they are allergic to.
If your child has a food allergy, teach them to be aware of the foods to avoid and all the possible names of those foods. You and your child should learn to read labels on food packaging and ask questions about served food. Your child should also know why it is important to look for an allergen in ingredients.
It is also important to tell all caregivers about your child’s allergy and any foods or drinks your child must avoid.
Airborne allergens
- Have a pet-free home. Or if you have a pet, keep it out of the child’s room and bathe it regularly.
- Remove carpets and rugs from the home, especially from your child’s bedroom. Hard floor surfaces do not collect dust as much as carpets do. If you have carpeting, you should try to vacuum at least once a week.
- Reduce the relative humidity in the home.
- Wash bedding in hot water. This will help reduce dust mites.
- Control contact with outdoor pollen by closing windows in peak seasons. Use an air conditioning system with a small-particle filter.
- Get rid of items in the home that collect dust. These include heavy drapes or old, unclean furniture.
- Clean your home often. Change your home furnace filter regularly as recommended.
- Seal pillows and mattresses if your child is allergic to dust mites.
- Keep bathrooms and other mould-prone areas clean and dry.
Taking care of your child with an allergy at home
If your child has a severe allergy, your doctor might give you a prescription for an epinephrine auto-injector such as an EpiPen or Allerject. Your doctor can show you how and when to use the auto-injector. You or your child may need to carry one at all times.
As much as possible, try to prevent allergic reactions by reducing your child's contact with the allergen(s). The steps you take depend on the substance to which your child is allergic. Discuss this with your child's doctor.
When to get medical help for an allergic reaction
Call 911 or take your child to the nearest emergency department if they have anaphylaxis. Signs and symptoms of anaphylaxis may include:
- hives, itching, redness of the skin
- swollen eyes, lips, tongue or face
- difficulty breathing, tightness of the throat or difficulty swallowing
- abdominal (belly) pain, nausea, vomiting or sudden onset of diarrhea
- coughing
- stuffy and/or runny nose, watery eyes, sneezing
- fainting, confusion, lightheadedness or dizziness
- rapid or irregular heartbeats
- cold, clammy, sweaty skin
- voice changes
Your child should go to the nearest emergency department even if they have received epinephrine, as the symptoms can start again after the epinephrine is given.
Virtual care services for children
Boomerang Health was opened by SickKids to provide communities in Ontario with greater access to community-based services for children and adolescents. For more information on virtual care services in Ontario to support a child with allergies, visit Boomerang Health powered by SickKids.