Allergies in children and how your doctor tests for them
16th July, 2021
Allergies in children are quite common. The Health Nuts Study* run by the Population Allergy Group of the Murdoch Children's Research Institute found that as many as one in ten of 12-month-old infants have a clinically confirmed food allergy – one of the highest reported rates in the world, so if you’re worried that your son or daughter might have an allergy then you should see your doctor.
Your doctor will help you work out whether their symptoms are caused by an allergic reaction, which is an immune system reaction - or an intolerance, which is an uncomfortable but unexplained reaction that doesn't have a clear immunological outcome.
Food allergies can be really uncomfortable and sometimes very serious
Allergies can have a big impact on a child’s life so being armed with that knowledge will help you manage their condition. If it’s a serious allergy it may be necessary to take extra precautions. Or you may find out that your child isn’t allergic to anything!
Common things that children are allergic to (allergens) are foods such as eggs, dairy, nuts, soy, sesame and seafood. They can also be allergic to pets (their skin dander), pollens, medicines, insect stings and house dust mites.
Food allergy can develop at any age, but it is most common in children less than five years old. Most children who are allergic to cow's milk, soy, wheat or egg, will outgrow their food allergy. However, allergic reactions to peanut, tree nuts, sesame seeds and seafood are less likely to be outgrown and can persist into adulthood.
What to expect when you take your child for an allergy test
Your doctor will ask when you’ve noticed symptoms appearing in your child and discuss their medical history, as well as the medical history of your family. They’ll use this information to determine which allergens to test. They might choose only a few, or they could test for up to twenty.
Allergy testing using skin prick tests or blood tests are the most commonly used tests for children.
Skin prick testing
There are no needles involved with skin prick testing. Skin prick testing is performed using prickers which look a bit like toothpicks. The prickers are dipped into allergen extracts. They are pointed, but do not usually draw blood, as the breaks made in the skin are only shallow. Some children say it is a little bit uncomfortable or ‘ouchy’, other children say it tickles. Their back may be quite itchy after the test is done. If they have an allergy to a substance, a swollen reddish bump will form, along with a ring around It, within 15-20 minutes. The test is usually over quite quickly and you can stay with them the whole time.
Blood tests (specific IgE tests) are another way to detect allergies. They measure the amount of IgE antibodies in the blood that have been produced by your child’s immune system in response to a suspected allergen. Your doctor may recommend a blood test if skin prick testing isn’t easily available, if your child has eczema or another skin condition, or if your child is taking medications that interfere with skin prick testing, such as antihistamines. Your child will have blood drawn, and the sample will be sent to a lab for testing. Multiple allergies can be tested with one blood draw and results usually take a few days.
If your child suffers from hives or a rash the doctor might do patch testing to investigate topical allergens. A paste with up to twenty allergens is put onto the skin, usually their back, and secured with tape. You have to keep the tape in place and dry for 48 hours ( easier said than done!). Your doctor will check the test sites regularly during this time for any reaction. If your child is sensitive to one of the allergens, they may develop a rash where the tape’s been applied.
Sometimes your doctor may decide to do an intradermal test if they suspect a medicine or insect sting allergy – this involves injecting a small amount of the allergen under the skin.
Childhood allergies are difficult to navigate and having your child's allergy diagnosed and treated can be stressful for you and for them. It’s important not to try diagnosing the issue yourself, for example by restricting your child’s diet to try to work out the source of an allergy. The key to avoiding misdiagnosis is to see your doctor.