How and When to Get Your Child Tested for Allergies

It never fails: You and your child head to the park only to have your trip cut short because they start sneezing, rubbing their nose, and sniffling—and soon you are both so miserable you cannot wait to get in the car and head home. Or, maybe your toddler breaks out in hives every time they take a bite of your omelet. Perhaps they get an all-over body rash after taking an antibiotic for an ear infectionor while playing with grandma's cat.

If these scenarios sound all too familiar, it is likely your child has allergies. But identifying the root cause on your own is nearly impossible. Are they allergic to pollen, grass, milk, eggs, penicillin, grandma's cat, or all of the above? The one thing that is clear is that it may be time to have your child tested for allergies. It's the only way to know for sure what's causing their symptoms.

To make this whole process a little less daunting, below we help you identify the signs of allergies as well as indicate when you should get your child tested. You will even find details on what types of allergy testing are available and what you can expect from testing.

Signs of Allergies in Kids

Allergic reactions can happen anywhere in the body, but the most common locations are the skin, eyes, stomach, nose, sinuses, throat, tongue, and lungs. Normally, these parts of the body are where the immune system cells are located. Their primary job is to fend off viruses and bacteria that are inhaled, swallowed, or that come in contact with the skin.

"The most important thing for parents to know is that the symptoms that often occur with allergies commonly occur from many unrelated causes," says David Stukus, MD, professor of clinical pediatrics in the division of allergy and immunology at Nationwide Children’s Hospital. "That is why it is always important to not self-diagnose allergies and to seek proper evaluation to clarify the diagnosis, as management can vary greatly depending upon the cause."

It is also important to note that no one person responds to an allergen in exactly the same way. Some kids may have one or two symptoms while others will have a multitude of symptoms. Likewise, some kids will have a mild allergic reaction to an allergen while others may have a life-threatening response—particularly to food, drugs, or bee stings.

For this reason, it is important to speak to a healthcare provider about what your child is experiencing so that an accurate diagnosis can be made.

Sometimes children will experience a severe, life-threatening allergic reaction. Known as anaphylaxis, this reaction can cause swelling in the lips and tongue, shortness of breath, vomiting, diarrhea, low blood pressure, fainting, and even death.

Most anaphylactic reactions are in response to food allergens, bee stings, latex, and drug allergies, but anything could potentially cause a severe reaction. Your child's doctor may prescribe an EpiPen if they feel your child is at risk for anaphylaxis. An EpiPen is an auto-injector that contains epinephrine, which is a safe and extremely effective medication that can reverse severe allergy symptoms. Even if your child uses their EpiPen to reverse a life-threatening reaction, they will still need immediate medical care.

When Your Child Should Get Allergy Testing

Your child can be tested for allergies at any age. But it is important to note that allergy tests are not meant to be screening tests. They should only be used when there is a medical history that suggests the presence of an allergy.

"Unfortunately, allergy tests are not good screening [tools]," explains Dr. Stukus. "We cannot just test for everything and see what comes back. [Allergy tests] are best utilized when the clinical history suggests the presence of allergy."

If you suspect that your child has allergies, you should discuss your concerns with your child's pediatrician and ask for a referral. From there, you will meet with a board-certified allergist for a consultation and testing.

They will likely want to know about your child's reactions, any patterns you have noticed, as well as any other pertinent information. Once your child is diagnosed, they may receive allergy testing every one to two years, depending on your child's treatment plan.

"Deciding whether or not to test a child for allergies should be based on each individual child and their symptoms," says Jaclyn Bjelac, MD, the associate director of the Food Allergy Center of Excellence in the Center of Pediatric Allergy and Immunology at the Cleveland Clinic. "Food allergies are not subtle. There is a very clear reaction to a food—and sometimes to more than one food. Testing is helpful in confirming a suspected allergy."

"When you use allergy testing as a screening tool, kids can end up being falsely labeled with a food allergy," she says. "If they are not having symptoms, then testing is not clinically relevant and you don't want to consider testing."

Different Types of Allergy Tests

If your pediatrician suspects that your child may have allergies or if they have exhausted all possible reasons for your child's symptoms, they may refer you to a board-certified pediatric allergist. Before the appointment, the allergist may ask that your child not take any type of antihistamine for seven days prior to the appointment, especially if they intend to perform testing at the first appointment.

The most common type of allergy test used in children is the skin prick test, or scratch test. However, this is not the only type of allergy testing available. Here is a closer look at each type of test and what you can expect from each.

Skin Prick Test (Scratch Test)

The skin prick test is the most common allergy test and is used to determine if there are IgE antibodies to certain allergens like foods, pollens, or pet dander.

"Skin prick tests apply a small amount of liquid allergen to the back or forearm and then a small scratch introduces it to the allergy cells in the skin," explains Dr. Stukus. "Within about 15 minutes, the presence of preformed allergy antibody will cause a small hive to develop."

With skin prick testing many allergens can be tested at the same time and the process is usually painless. If your child is allergic to more than one thing, they may have multiple hives on their back or forearm. They also may feel a little itchy.

Blood Test

The blood test that is most often used for allergy testing is called RAST (radioallergosorbent test). Blood tests are used when skin tests can't be done. For instance, if your child has a skin condition or recently had a severe allergic reaction, your allergist may opt for a blood test instead of a skin test. It is important to note that a positive blood test does not always mean that your child has an allergy.

"Blood IgE tests measure levels of allergy antibody in the blood," Dr. Stukus says. "Both skin and blood IgE tests detect sensitization but do not actually diagnose allergy by themselves. They are often misinterpreted and lead to over-diagnosis of allergy when someone has sensitization but is otherwise tolerant."

Patch Test

Allergists, and sometimes dermatologists, will use patch tests to detect delayed allergic reactions. Some allergic reactions sometimes take several days to develop. During the patch test, allergens are applied to patches, which are then placed on your child's skin and then checked in about 72 hours.

"Patch tests are often used in people who have long-term rashes that cannot be explained," says Dr. Bjelac. "It also can be used to test allergies to dyes and fragrances."

Intradermal Test

Sometimes an allergist will perform an intradermal test where a small amount of allergen is injected just under the skin. This type of skin testing is more sensitive than skin prick testing.

"The intradermal test is the next step of skin prick testing," explains Dr. Bjelac. "During this test, the needle goes into intradermal space and introduces a little more of the allergen. For instance, it might be used if someone comes in with symptoms to a dog—an intradermal test may be used to see if they react."

This type of test also may be used to check for a drug allergy after getting a negative skin prick test.

Food Challenge Test

During this test, a very small amount of the allergen is given to the child by mouth or it is breathed in. Only a challenge test can determine how severe an allergy is or if a child has outgrown an allergy.

"A food challenge test is the gold standard of food allergy testing," says Dr. Bjelac. "It should only be done under close supervision of an allergist in their office that way they can treat any allergic reactions if they happen and quickly administer medicines to keep them safe."

Elimination Test

Sometimes when food allergy testing is inconclusive or if the allergist suspects an intolerance, they may use an elimination test. During this test, you will avoid feeding your child whatever foods the allergist thinks might be making them sick.

Your child's allergist will tell you how long to avoid the food. Some foods take longer to be completely out of your child's system than others. Then, when advised to do so, you will add back in each of the foods you eliminated, one at a time. During that time, you will look for signs of an allergic reaction and share your results with the allergist.

Other Considerations

It is important to note that with many of the allergy testing methods, there is a possibility for a false positive. Many times kids are diagnosed with a food allergy even when they have no history of an allergy and have been eating the food without symptoms, says Dr. Bjelac.

In fact, about 50% to 60% of all skin prick tests produce a "false positive," meaning that the test shows a positive result even though your child is not really allergic to the food being tested.

"Both skin and blood IgE tests have high rates of false-positive results and neither of them can determine how severe someone’s allergies are," says Dr. Stukus. "They can only be used to determine the likelihood of an allergy being present, which is based upon the clinical history."

By contrast, the likelihood that you will get a false negative is slim. In other words, if your child does not test positive for a particular food or substance, they are likely not allergic to it. In fact, research indicates that getting a negative skin prick test result is accurate 95% of the time.

What to Do If Your Child Tests Positive for an Allergy

How you move forward after an allergy diagnosis largely depends on the type of allergies your child has, as well as the severity.

In general, it is important to remember that an allergic reaction is a response to something—whether that is pollen, food, pets, drugs, or something else. Overall, the best way to avoid allergic reactions is to avoid the allergens. This may require not eating the offending food if they are diagnosed with a food allergy or avoiding homes with cats if they are allergic to cat dander.

Most allergists will provide some type of education regarding your child's allergies. Typically, this involves everything from what you need to avoid to how to use an EpiPen if one is prescribed. You also may be instructed on how to change your lifestyle if your child has a food allergy or what changes need to be made in the home to make your child more comfortable if they have environmental allergies.

"Each person should be managed as an individual based upon their history, symptoms, and preferences in regards to treatment options as well as other factors such as home environment and exposures," says Dr. Stukus. "Understanding of risk for reactions from various exposures is incredibly important to help each family determine the best management strategy moving forward."

As your child gets older, there may be other options for dealing with allergies like allergy shots or even oral immunotherapy for food allergies.

"What we know now compared to what we knew five or 10 years ago is so different," Dr. Stukus says. "Having a child diagnosed with an allergy can feel overwhelming and scary, especially in the food allergy space. That's why it is so important to connect with a board-certified allergist who is up to date on the latest [research]. Caregivers should leave the allergy office feeling empowered and not feeling hopeless."