Allergy Blood Test: Types, Accuracy And Results

September 14, 2023

Allergy Blood Test: Types, Accuracy And Results

Around 50% of children in the UK have one or more allergies which occur when antibodies react to an allergen. The immune system is triggered and inflammation can occur in the skin, sinuses, airways, and digestive system.

Although symptoms can be mild for some, they can be severe for others. It’s important to recognise the signs and seek proper treatment to manage allergies in children.

Discovering what allergies a child has is important so you can avoid the trigger and manage their symptoms. An allergy blood test can reveal the allergen that’s causing the reaction and help you keep your child safe from future reactions.

This page will look at common allergies in children, the symptoms that accompany them, what an allergy blood test is and how they can help.

A paediatric doctor examning a child's arm for signs of an allergy.

Common types of allergies

Some allergies are more common in children than others. Common allergies can include:

  • Tree and grass pollen – this is often called hay fever
  • Dust mites allergy
  • Food allergy – peanuts, milk, and eggs are the most common
  • Animal fur allergy – cat and dog fur in particular
  • Insect sting allergy – bee and wasp stings can cause allergic reactions
  • Medication allergy

Allergy symptoms

Symptoms of an allergic reaction in children and babies can vary slightly from those in adults, as children may not be able to communicate how they’re feeling. This is why parents should know what to look out for.

Allergy symptoms in children and babies can include but aren’t limited to:

  • Abdominal pain
  • Coughing
  • Diarrhoea
  • Dry skin – skin conditions like eczema can also flare up
  • Headaches
  • Rashes on the skin
  • Itchy, watery, red eyes
  • Nausea
  • Vomiting
  • Shortness of breath
  • Sneezing or a runny nose
  • Sore throat
  • Swollen lips, tongue, eyes or face
  • Wheezing

Hay fever symptoms can be fairly mild and tend to show as itchy eyes, sneezing, or having a runny nose.

Anaphylaxis is a severe allergic reaction and requires immediate medical attention. This type of reaction can occur in response to food, insect stings, and other allergens.

Signs of anaphylaxis include:

  • Swelling – this includes the tongue, throat, and face
  • Wheezing
  • Shortness of breath
  • Difficulty swallowing

Allergy tests

If you think that your child may have an allergy, you should get them tested as soon as possible. This will ensure you can avoid the allergen and have the appropriate treatment if they have a reaction in the future.

There is a range of allergy tests that can be done to determine what your child is allergic to.

The types of allergy tests are:

  • Skin prick or patch tests – a small amount of an allergen is put into the skin to see if a reaction occurs
  • Blood tests – a blood sample is taken and analysed to check which allergens are causing the reaction
  • Special diets – a food plan will eliminate certain foods to see what happens to the allergy symptoms

What is an allergy blood test?

An allergy blood test is a diagnostic test used to check for antibodies called immunoglobulin E (IgE) in your child’s blood to see what allergen has caused this response. The test will only take a few minutes, and the sample will be taken by a medical consultant.

Try to keep your child calm before and during the test by speaking of it positively beforehand. If they’re especially nervous, a numbing cream or spray can sometimes be used.

Types of allergy blood tests

Two different types of allergy blood tests can be done.

The types of allergy blood tests are:

  • Total IgE test – this measures the total amount of IgE in their blood. This test doesn’t define what the allergen is, it just confirms that an allergic reaction is happening.
  • Specific IgE test – this measures the IgE in their blood in response to a specific allergen. This test can help to define which allergen is causing the reaction.

Allergy blood test accuracy

Allergy blood tests can sometimes give a false-positive result. False-positive results can lead you to believe your child has an allergy when they don’t.

These false positives can occur if the body reacts to something it hasn’t experienced in a while – for example, certain foods that aren’t eaten regularly can be the cause of this.

With this in mind, our medical consultants will use their expert knowledge to determine if something is a false positive and if further testing is needed.

How long do allergy blood test results take?

Allergy blood test results can be ready within 72 hours, but they can take 2-3 weeks in some cases. You’ll be advised on how long they’ll take during the appointment by the medical consultant doing the test.

The results of a skin prick test will be available immediately, as they are checked in clinic. However, patch tests take a few days to complete, since the patches are usually left on for 48 hours before being removed and examined by a healthcare professional.

Allergy blood test results explained

Allergy blood test results can vary from clinic to clinic, as the scoring system used can be different. Everybody has some IgE in their blood, so your child’s results will show some IgE regardless.

The results won’t indicate how severe an allergy is, just if they do have an allergy. A positive result will mean that there’s a higher presence of IgE, and a negative result will mean that their levels are within the normal range. A negative result means that your child probably doesn’t have an allergy.

Allergy blood test results need to be interpreted by a paediatrician or referred to allergy specialists. This can help you understand if your child does truly have an allergy and if you need to take any precautions such as avoidance and carrying antihistamine medications or an adrenaline auto-injector (EpiPen).

Book an allergy blood test with Childhealthy

If you think your child may have possible allergies, book an appointment to see a paediatrician, who may request an allergy blood test. Our expert level of care and ability to make your child feel at ease during the appointment can ensure that this is a positive experience for you and your child.

You can easily book your child an allergy blood test through our website and experience our professional paediatric services.

Additionally, we provide a full nutritional assessment for infants that will help you ensure your baby is getting the nutrition he or she needs while avoiding allergens they might have.






Disclaimer: Information contained in this article is intended as general advice and does not replace a medical assessment. If you are concerned about your child please contact your doctor for advice.


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