You're sitting with your family having an afternoon snack, when your child starts itching, swelling, feeling nauseous and having trouble breathing. It’s a parent’s worst nightmare, and you have no idea why it’s happening. It seems like an allergic reaction, yet your child, to the best of your knowledge, has no known allergies. You rush to the hospital, wondering what went wrong and if it could have been avoided.
This is exactly what happened to Cassie Pellerin after snacking on a pumpkin seed, as she had done many times before. She immediately began to feel sick, broke out in hives and felt itchy all over. Confused by this new reaction, her parents rushed her to the hospital. From there, they took Cassie to have an allergy test.
There are three different types of skin tests, but the skin prick allergy tests are the most common. The doctor or specialist will place a drop of solution containing the allergen on the patient’s arm or back while a series of scratches and pricks allow the solution to sink into the skin. If a reaction ensues, this means the person has an allergy to that item. If it’s a food allergen, a reaction in the skin prick test doesn't always mean you will react when you ingest that item, but the bigger the hive the bigger the possibility.
“We never had any reason at all to have Cassie tested for food allergies,” says Cassie’s mother, Terri. She says the specialist was “very surprised by Cassie’s extreme reaction to pumpkin seeds since it was so rare.
“She decided to test for a wide variety of foods and plants while we were there. With the protein prick tests, she confirmed that Cassie was definitely highly allergic to pumpkin seeds. Luckily, she also identified a strong allergy to cashews and pistachios, which we never would have otherwise known.”
Teens and tweens like Cassie find this skin prick test fairly tolerable.
“I didn't really like the allergy testing but I didn't mind it either. The prick tests were slightly uncomfortable because the things I was allergic to swelled and became extremely itchy but I wasn't able to itch them. I was happy to have the doctor confirm the allergies that I knew I had, and I was interested to learn about my other allergies, like cockroaches,” says Cassie. “Now I carry an EpiPen everywhere I go.”
Allergist Jessica Clarke (not the allergist who treated Cassie) thinks the skin prick allergy test is very useful. “Skin testing is something I use daily in my allergy practice to help diagnose allergies. It is a very safe test and causes minimal discomfort, usually the worst part is the itchiness,” says Dr. Clarke.
While Dr. Clarke uses the skin prick test “multiple times every day as it is the main tool for diagnosing allergies,” she believes that “only patients showing signs and symptoms of an allergy should be tested.”
Allergies can develop at any age
“Sometimes allergies develop as children get older,” says allergist Jessica Clarke. “Pollen allergies often develop after the age of five, once kids have had more seasons of pollen exposure. However, we do see them in younger children as well.”
Symptoms will present themselves
“In terms of environmental allergies, runny nose, nasal congestion, sneezing and itchy, watery, puffy eyes are symptoms of allergies. If parents notice these symptoms outside of a cold, it may be worth speaking with their family doctor to see if an allergy is possible. The family doctor can then refer them to an allergist for testing,” says Dr. Clarke. “Food allergies generally happen shortly after the culprit food is consumed. They may cause hives, swelling, cough, wheezing, shortness of breath, vomiting, abdominal pain, lightheadedness or dizziness.”
Allergy test results can vary.
“Negative and positive histamine controls are usually done to help read the skin testing as it can be challenging in patients with sensitive skin,“ says Dr. Clarke. “We want to make sure we don’t miss an allergy if someone takes a medicine (an antihistamine for example) that might interfere with the testing. False positive and false negative testing can occur, so skin testing should always be interpreted in conjunction with the patient’s history.”
Originally published in ParentsCanada magazine, July/August 2015.