Key points about allergy
- allergies happen when your child's immune system mistakenly treats normally harmless substances as 'harmful'
- the substances causing allergies are called allergens
- the immune system then releases histamine and other chemicals that cause symptoms
- environmental/airborne allergens (such as house dust mites, pollen, pets) can cause 'hay fever' (allergic rhinitis) - sneezing, itchy eyes and a runny or blocked nose
- food allergy (and also bee or wasp stings, latex, medicines) can cause mild reactions such as hives and itching, to severe symptoms called anaphylaxis
- anaphylaxis is a life-threatening allergic reaction which needs urgent medical treatment
What is an allergy?
Allergies happen when your child's immune system mistakenly treats normally harmless substances as 'harmful'. The substances that trigger allergies are called allergens. Your child's immune system overreacts to the allergen by making allergic antibodies (IgE) against the allergen. The immune system then releases histamine and other chemicals that cause symptoms.
There are many types of allergens found in our environment. The most common of these are:
- airborne allergens that come from dust mites, cats and dogs, pollen, moulds
- food allergens
- insect stings
- other things such as medicines or latex
Once your immune system has made IgE against an allergen, coming into contact with that allergen can result in an allergic reaction, with symptoms that can range from annoying to life-threatening.
Who gets allergies
It's not clear exactly why some people have allergies and others don't.
The tendency to develop allergies is usually passed down through your genes. But, not everybody in a family will have the allergies. Members of the same family may have allergies to different things and some people may develop allergies when no other member of the family has any. When a child is allergic to one thing, it is likely that they may be allergic to other substances as well.
As well as family history, many factors in the environment may have an impact.
Signs and symptoms of allergies
The symptoms of an allergy vary according to what a child or young person is allergic to.
Airborne allergens
Airborne allergens such as pollen usually cause 'hay fever' (allergic rhinitis). Children with 'hay fever' may have seasonal symptoms with a runny, itchy nose or eyes and sneezing during grass pollen season. Children who are allergic to dust mites may have year-round 'hay fever', with a runny or blocked nose and sneezing, often worst in bed. Airborne allergens can also contribute to the symptoms of asthma and eczema.
Food allergies
Symptoms
Children with food allergies get symptoms every time they eat a food they are allergic to.
Symptoms of food allergy can include:
- skin rashes (such as hives or welts)
- swelling of the face, lips and eyes
- tummy pains, vomiting and diarrhoea
Symptoms of a severe reaction
Some children may have a severe reaction with breathing problems (for example, cough and wheeze) or collapse.
This is called anaphylaxis and can be life-threatening. Please dial 111 within New Zealand (use the appropriate emergency number in other countries).
Common concerns about food allergy
If your child is allergic to a food, touching that food is very unlikely to cause a severe allergic reaction. Some skin rashes may appear on the part of the skin the food has touched.
Being in the same room as the food is also very unlikely to cause a reaction. But, cooking vapours from some foods, such as egg or fish, may trigger a reaction in some people.
Diagnosis of allergies
A health professional usually diagnoses allergies once they have listened to your story and examined your child.
Environmental allergies may be obvious from your child's story (for example, your child gets itchy and sneezy every time they pat a cat). But sometimes, your child might need testing for these allergies.
If food allergy is suspected, your child may need an allergy test (skin tests or a blood test for specific allergic antibodies, previously called a RAST) to confirm what they are allergic to. This is to make sure you know what foods your child needs to avoid. In some cases, your child might need to go to a paediatric clinic or specialist.
In pēpi (babies) and young tamariki (children), some food allergies are not caused by IgE antibodies. These food allergies are known as 'non-IgE-mediated food allergies'. These types of allergies can take a long time to diagnose and you will often need the help of a paediatrician or specialist and dietitian.
Most common airborne allergens
Some of the most common things people are allergic to are carried through the air. These include:
- dust mites which live in carpets, bedding and upholstery
- pollens from trees, grasses and other plants
- animals such as cats, dogs and horses
- moulds, which thrive in warm, dark, moist places, such as bathrooms, basements and outdoors in compost heaps
Managing food allergies in children
Avoiding the allergen
Once your health professional, paediatrician or specialist diagnoses your child's food allergy, managing it includes avoiding the allergen. Make sure your child also avoids all the different products containing the allergen and the different forms it might come in. Families often need help from a dietitian to do this.
Action plans for allergic reactions or anaphylaxis
All children with food and insect sting allergy need to have an action plan for allergic reactions or anaphylaxis. These explain how to manage an allergic reaction.
Children with food allergy need follow up to see whether their food allergies are going away. ASCIA (the Australasian Society of Clinical Immunology and Allergy) has developed several action plans for use in Australia and New Zealand.
The ASCIA website has a range of action plans you can use.
'Non-IgE-mediated' food allergy
Some young tamariki have different types of food allergy called 'non-IgE-mediated' food allergy. These conditions can be harder to identify and are more common in pēpi and very young tamariki.
Food allergy and asthma
Some tamariki with food allergy also have asthma. It is important they have asthma medicines and an asthma management plan to keep their asthma under control. Having asthma can make an allergic reaction to food more severe. If your child is using their reliever inhaler more than a couple of times a week, or they are more breathless, wakeful at night or coughing more, you should see your health professional.
Avoidance of airborne allergies is sometimes possible.
You can use medicines such as nasal sprays and antihistamines to treat hay fever (allergic rhinitis).
Check out the advice on allergy minimisation on the ASCIA website.
The most common food allergens
These include:
- milk (dairy)
- eggs
- tree nuts and peanuts
- fish and shellfish
- sesame
- soy
- wheat
Almost any food can trigger an allergy in some tamariki and rangatahi (young people).
Other common allergens
These include:
- insect stings (bees and wasps)
- medicines
- latex
What is anaphylaxis?
Anaphylaxis can be life-threatening - it's an emergency that needs immediate treatment.
Anaphylaxis is the most severe form of allergic reaction and can be life-threatening. Anaphylaxis is an emergency that needs immediate treatment with an injection of a medicine called adrenaline (epinephrine). This is the medicine in automatic injectors such as the EpiPen®. The child or young person needs to lie down - they must not stand or walk. If breathing is difficult, allow them to sit.
Call 111 within New Zealand for an ambulance (use the appropriate emergency number in other countries).
