Allergies happen when your body’s immune system reacts to substances in the environment (‘allergens’) that are normally harmless to most people – for example, food, insect stings or bites, dust mites, animals, pollen and so on.
How allergies happen
Allergies happen when your child comes into contact with something in the environment that he’s allergic to. This thing is called an allergen, and for most people it’s something harmless, like food, dust mites or pollen.
The allergen enters the body and your child’s immune system reacts to it. This reaction causes the release of histamine. When histamine gets released into the body, it can cause symptoms like an itchy rash or skin swelling.
Mild, moderate and even severe allergic reactions are common, but deaths from allergic reactions are rare. Deaths are usually caused by a delay in the person receiving life-saving medication.
Allergic reactions: how quickly do they happen?
An immediate allergic reaction usually happens within minutes or up to 1-2 hours after your child comes into contact with or eats the substance that she’s allergic to.
A delayed allergic reaction usually occurs between 2-4 hours and many days after exposure to the substance your child is allergic to.
Symptoms of allergies
If the allergic reaction is mild or moderate, your child’s symptoms will usually include one or more of the following:
- rash, hives or welts
- swelling of the face, eyes or lips
- tingling mouth
- abdominal pain or vomiting (but if this happens after an insect sting, it means your child is having a severe allergic reaction).
In other cases of mild or moderate allergic reactions, allergens like pollen, animal fur or house dust mites can cause symptoms of hay fever and asthma.
Some allergens – for example, food, insect stings and medications – can cause severe allergic reaction or anaphylaxis. In this case, your child might have one or more of the following signs or symptoms:
- difficult or noisy breathing
- swelling of the tongue
- swelling or tightness in the throat
- trouble talking and/or a hoarse voice
- a wheeze or persistent cough
- persistent dizziness or fainting
- low blood pressure.
Young children might go pale and floppy.
Anaphylaxis is life-threatening and requires urgent medical attention. Call an ambulance immediately – phone 000. While you’re waiting for the ambulance, lay your child flat to help keep his blood pressure stable.
Testing for allergies
If you think your child might have allergies, getting a proper diagnosis is important.
To start this process, you can talk to your family GP, who can refer you to an allergist or immunologist (a medical doctor with specialist training in allergic diseases) for the following tests:
Skin-prick test: the allergist will put a small amount of the suspected allergen on your child’s skin. The allergist will then prick your child’s skin with a small device that looks a bit like a toothpick. A red lump might come up where the skin has been pricked.
Blood tests: the serum specific IgE antibody test uses your child’s blood to see whether she’s sensitive to specific allergens. Your child might have this test if she can’t have skin-prick testing because she has severe eczema or has taken an antihistamine.
You might hear about tests like IgG
food antibody testing, Vega testing and hair analysis. These tests haven’t been scientifically validated as allergy tests. Tests and treatments that are backed up by science are most likely to work, be worth your time, money and energy, and be safe for your child.
Treatment for allergic reactions
The way you treat an allergic reaction depends on how severe the reaction is.
If your child ever has difficulty breathing while having an allergic reaction (anaphylaxis), call an ambulance immediately by phoning 000.
Giving your child a dose of antihistamine (in tablet or syrup form) is appropriate if you think your child is having a mild to moderate allergic reaction like a skin rash, tingling mouth or swelling.
In fact, having some antihistamine syrup in your home’s first aid kit is a good idea – this way it’s handy when you need it. You don’t need a prescription to buy antihistamine syrup in Australia.
Some antihistamines can make your child sleepy, which can look like anaphylaxis and make it hard to know what reaction your child is having. It’s best to use antihistamines that won’t make your child sleepy (non-sedating). Your pharmacist or GP can advise you on the most appropriate brand for your child.
Other treatments for allergies
Depending on the kind of allergic reaction your child has, he might need other treatments. For example, if he has eczema he might need corticosteroid creams or ointments. Asthma treatments include inhalers like Ventolin® or Asmol. If your child has a severe asthma attack, call an ambulance.
Your doctor can give you an action plan to treat your child’s allergic reactions, asthma and eczema. The action plan usually includes important information on the management of allergic reactions and medications to use, as well as how to respond to an allergic reaction.
Children who have persistent and troublesome allergies to insect stings, house dust mites and grass pollen might have immunotherapy to cure them of their allergy. Immunotherapy is currently not available for food allergies.
If your child has asthma as well as an allergy to something, it’s important to control her asthma well.
Managing allergies and allergic reactions
If your child is at risk of anaphylaxis, he’ll often be prescribed an adrenaline auto-injector – for example, EpiPen® or Anapen®. He’ll probably also have an ASCIA (Australasian Society of Clinical Immunology and Allergy) action plan.
If your child is prescribed an adrenaline auto-injector, it’s important that both you and your child learn how and when to use it (your child’s ability to use it will depend on her age and development). You should carry the adrenaline auto-injector at all times. You can also teach others – family, friends, teachers and carers – how to use it.
It’s also usually a good idea for your child to wear a medical bracelet that lets people know about his particular allergy.
Allergies or intolerance?
Note that allergies are different from intolerances.
Mild to moderate intolerance doesn’t involve the immune system, but sometimes symptoms of mild or moderate food allergy look like the symptoms of food intolerance. It’s essential that your child’s food allergy is confirmed by a clinical immunology or allergy specialist.
Our article on recognising food allergies and intolerances has more information.
Most children with allergies to egg, cow’s milk or wheat outgrow their allergies by the time they’re five years old. Peanut, treenut, fish and shellfish allergies are more likely to be lifelong.