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Allergy in Children: Allergy Test, Symptoms, and More
How Are Common Childhood Allergies Diagnosed? A Parent’s Guide to the Allergy Test
Watching your child suffer from sneezing, hives, or an upset stomach can be distressing, and the cause is often a mystery. Many of these symptoms point towards a common childhood allergy, an overreaction of the immune system to a normally harmless substance. Understanding how to diagnose allergies is the first critical step toward managing them effectively and improving your child’s quality of life.
In this article, we will explore the nuances of skin tests, blood tests, and challenge tests, demystifying the journey to a conclusive allergy diagnosis and empowering you to help your child find relief from their allergy.
What Exactly Is an Allergy in Children?
An allergy is a condition in which the body’s immune system overreacts to a substance that is typically harmless to most people. This substance is known as an allergen.
When a child with an allergy comes into contact with something they’re allergic to, their immune system thinks it’s a harmful threat and makes special antibodies called IgE. These antibodies stick to certain cells called mast cells.
The next time the child encounters that allergen, the IgE signals the mast cells to release chemicals like histamine. This rush of chemicals causes the typical allergy symptoms, like itching, swelling, or trouble breathing.
Allergies in kids usually develop because of a mix of genetics and the environment. If a parent or sibling has allergies, the child is more likely to get them too. Many kids follow an “allergic march,” starting with eczema as babies, then food allergies as toddlers, and later hay fever or asthma.
Common triggers include things in the air like pollen, dust mites, mold, and pet dander, as well as foods like milk, eggs, peanuts, shellfish, insect stings, and some medicines.
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What are the Common Signs and Symptoms of Allergies in a Child?
Allergy symptoms in kids can look very different depending on what they’re allergic to.
For allergies to things in the air like pollen or dust mites, common signs include sneezing a lot, a runny or stuffy nose, itchy and watery eyes, and an itchy throat or ears. Parents might also spot things like dark circles under the eyes (called “allergic shiners”) or notice their child rubbing their nose upward often.
Skin allergies usually show up as eczema (dry, itchy patches), hives (raised, itchy bumps), or a rash that appears after touching something irritating.
Food allergies can cause different problems and sometimes more serious ones. A child might have an itchy mouth, a tingling throat, swelling of the lips, tongue, or face, hives, stomach cramps, vomiting, or diarrhea shortly after eating the food.
In rare but severe cases, food allergies can cause anaphylaxis (a life-threatening reaction) with symptoms like trouble breathing, wheezing, a sudden drop in blood pressure, a fast but weak pulse, confusion, or feeling very unwell. Knowing these symptoms helps parents act quickly and get the right care.
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How Do You Diagnose a Childhood Allergy? The Role of the Allergy Specialist.
If you think your child might have an allergy, the first step is to talk to a healthcare professional who may refer you to an allergist (a doctor who specializes in allergies, asthma, and immune system issues). The allergist will start by asking detailed questions about your child’s symptoms.
It helps to keep a diary before the appointment, noting when symptoms happen, how long they last, and what your child was doing or eating at the time. Taking photos of any rashes or swelling can also be really helpful.
The allergist’s main job is to figure out whether your child’s symptoms are due to a true allergy, which involves the immune system, or something like a food intolerance, which doesn’t. Based on your child’s history, the doctor will decide if allergy tests are needed to pinpoint the triggers.
Getting the right diagnosis is key. It helps avoid unnecessary restrictions while making sure your child can safely avoid what causes their reactions and stay healthy and comfortable.
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What is a Skin Prick Test and How Does it Work for an Allergy Diagnosis?
The most common allergy test is the skin prick test (SPT). It’s quick, safe, and helps check for immediate allergic reactions (like those caused by pollen, dust mites, pet dander, mold, or certain foods). During the test, the allergist places a small drop of each allergen on your child’s forearm or back and gently pricks the skin underneath with a tiny, sterile tool. A positive control (histamine) and a negative control (saline) are also included to make sure the test is working properly.
Within about 15 to 20 minutes, if your child is allergic to something, you’ll see a small, itchy bump with some redness similar to a mosquito bite. It’s important to stop any antihistamines several days before the test, since these can block reactions and affect the results.
In some cases, doctors might use intradermal testing, which is a bit more sensitive. This involves injecting a small amount of allergen just under the skin. It’s often used when the skin prick test comes back negative but there’s still a strong suspicion of an allergy, especially to things like insect stings or certain medications. Because this test is more sensitive, there’s a slightly higher chance of a stronger reaction, so it’s done under close supervision.
Another kind of test, the patch test, is used for detecting delayed skin reactions, like those from contact allergies (e.g., nickel, fragrances, or latex). In this test, patches containing small amounts of different allergens are placed on the skin and left on for 48 hours. The doctor checks for any red, itchy areas after the patches are removed and again a day or two later, since these reactions take longer to show up.
When Is a Blood Test Necessary to Diagnose Allergies?
Sometimes, a specific IgE (sIgE) blood test is used instead of a skin test, especially if your child has eczema, can’t stop antihistamines, or is at risk of a serious reaction. It involves a simple blood draw to check for IgE antibodies to specific allergens.
These tests can show if your child is sensitized to something, but a positive result doesn’t always mean they’ll react. That’s why an allergist needs to interpret the results alongside your child’s symptoms and history. In some cases, a more advanced test called component-resolved diagnostics (CRD) may be used to help predict how serious a reaction could be.
What Is an Oral Food Challenge Test and Why Is It Used?
The oral food challenge (OFC) is the most accurate way to confirm or rule out a food allergy. It’s usually done when test results are unclear or to see if a child has outgrown an allergy, like to milk or eggs. Because there’s a risk of a serious reaction, it’s always done in a medical setting under close supervision.
During the OFC, the child eats small, increasing amounts of the suspected food over a few hours while being monitored. Sometimes the food is hidden (blinded) to avoid bias. If no symptoms appear after eating a full portion, the food is likely safe. If a reaction occurs, the test is stopped, and treatment is given right away. The OFC gives clear, reliable answers to guide next steps.
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Can an Allergy Trigger Asthma Symptoms in a Child?
Allergies and asthma are closely connected, especially in kids. Most children with asthma actually have allergic asthma, where their asthma symptoms are triggered by things like pollen, pet dander, or dust mites. This happens because the nose and lungs are part of the same airway system. So, inflammation in the nose (like from hay fever) can affect the lungs too.
When a child with allergic asthma breathes in an allergen, their immune system overreacts, causing not just sneezing or a runny nose, but also swelling and tightening in the lungs. This leads to coughing, wheezing, and trouble breathing. Figuring out and treating the child’s allergies can make a big difference. Reducing asthma flare-ups and often lowering the need for medications.
Identifying Allergy Triggers and What Comes Next
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The main goal of allergy testing is to go from a general suspicion to clearly identifying what the actual trigger is.
To do this, an allergist looks at three things: your child’s symptoms and medical history, results from skin or blood tests, and sometimes the outcome of a food challenge. A positive test alone doesn’t mean your child is allergic, but it just means their immune system has noticed that substance before. It only becomes meaningful if the test result matches real-life symptoms.
For example, if a child tests positive for dust mites and has year-round sneezing and wheezing at home, that’s likely a true allergy. But a positive test to shrimp in a child who eats shrimp with no problems? Probably not an issue.
Once a specific allergy is confirmed, the allergist will work with you to create a personalized plan. The first step is usually avoiding the trigger, like using dust mite-proof covers, HEPA filters for pollen, or reading food labels carefully. The plan might also include medications, such as antihistamines for sneezing or nasal sprays for congestion, and creams for eczema.
If your child has a food or insect sting allergy that could cause a serious reaction, they’ll be prescribed an epinephrine auto-injector (like an EpiPen) and given an Allergy Action Plan to share with caregivers and school staff. In some cases, especially for environmental allergies, allergy shots or tablets may be recommended to help your child build long-term tolerance.
Summary
- An allergy happens when the immune system overreacts to something harmless, like pollen or certain foods, by releasing chemicals like histamine.
- In kids, allergies can show up as sneezing, runny nose (hay fever), skin rashes (like eczema or hives), tummy troubles, or swelling after eating certain foods.
- To figure out if it’s really an allergy, a doctor (usually an allergist) looks at your child’s symptoms, medical history, and may run some tests.
- A skin prick test is a quick way to check for immediate allergic reactions by placing tiny amounts of allergens on the skin and watching for a reaction.
- A blood test can measure IgE antibody levels—helpful if your child can’t stop allergy meds or has skin issues like eczema.
- An oral food challenge is the most accurate test for food allergies. It’s done in a medical setting because it involves eating the suspected food slowly while being closely watched.
- Many kids with asthma also have allergies (known as allergic asthma) and managing the allergy often helps control the asthma.
- Once diagnosed, the allergist will create a plan that usually includes avoiding triggers, using medications if needed, and having an Allergy Action Plan ready in case of a serious reaction.
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Further Reference
- All About Allergy Testing | AAAAI [Internet]. Aaaai.org. 2022. Available from: https://www.aaaai.org/Tools-for-the-Public/Conditions-Library/Allergies/all-about-allergy-testing
- Sicherer SH, Sampson HA. Food allergy: A review and Update on epidemiology, pathogenesis, diagnosis, prevention, and Management. The Journal of Allergy and Clinical Immunology [Internet]. 2018 Jan;141(1):41–58. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29157945
- Boyce JA, Assa’ad A, Burks AW, Jones SM, Sampson HA, Wood RA, et al. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary of the NIAID-Sponsored Expert Panel Report. Journal of Allergy and Clinical Immunology. 2010 Dec;126(6):1105–18.
- Food Allergy | NIH: National Institute of Allergy and Infectious Diseases [Internet]. Nih.gov. 2018. Available from: https://www.niaid.nih.gov/diseases-conditions/food-allergy
- Guidelines for the Diagnosis and Management of Food Allergy in the United States Summary for Patients, Families, and Caregivers National Institute of Allergy and Infectious Diseases [Internet]. Available from: https://www.niaid.nih.gov/sites/default/files/faguidelinespatient.pdf
- Chin B, Chan ES, Goldman RD. Early exposure to food and food allergy in children. Canadian Family Physician [Internet]. 2014 Apr;60(4):338. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC4046529/
- Food Allergies and Intolerances in Newborns and Infants [Internet]. Aap.org. 2020 [cited 2025 Jul 31]. Available from: https://www.aap.org/en/patient-care/newborn-and-infant-nutrition/food-allergies-and-intolerances-in-newborns-and-infants/?srsltid=AfmBOorACNrpsH0fM86xpzGIc0M8Csn4Vgchg47J9Wjq_AJmsduyuFCd
Disclaimer: This article is for educational purposes only. Please consult your healthcare provider for personalized medical advice.
