What Causes Allergy Cross-Reactivity

a case of mistaken allergen identity
What Causes Allergy: Child Sneezing Into Tissue
© Can Stock Photo / LyubovKobyakova

Most of us are familiar with the common signs and symptoms associated with severe allergies. These include: tingling or itching in and around the mouth, swelling of the face, lips, tongue, and throat, wheezing, restricted breathing, abdominal pain, diarrhea, nausea or vomiting, dizziness, lightheadedness or even fainting. Being a seasoned vet, you know when to dial 9-1-1 when those types of allergic reactions occur. But are you familiar with allergy cross-reactivity, where the proteins in a known primary allergy can be misidentified by your immune system in other substances, especially foods? Here are some of the main allergies and associated foods that may be subject to allergy cross-reactivity.


If your child reacts to latex, they are much more likely than other children to suffer from allergy cross-reactivity. Foods like avocados, bananas, chestnuts, and kiwis are high in proteins that look similar to some of those found in natural rubber latex. Your child may also be sensitive to apples, carrots, celery, melons, papaya, potatoes and/or tomatoes. If you're thinking, “…my child is allergic to latex but definitely does not have the same type of reaction with any of these foods,” I would encourage you to try removing them from their diet and re-introducing them systematically under the supervision of a medical professional before you assume you’re in the clear. While allergies to latex rubber develop on contact and almost immediately, food allergies related to consumption of some of the aforementioned foods typically develop much more slowly and are generally less severe.

Pollen and Seasonal Allergies

Does your child suffer from seasonal allergies? There are cases where children experience mild to moderate itching around the mouth and throat (sometimes described as tingling in the mouth) soon after eating raw fruits and vegetables. This can be a sign of allergy and the child should be assessed by a health professional for possible oral allergy syndrome (OAS) or pollen food sensitivity, when your body can’t tell the difference between the food and pollen. The good news is that those with OAS don’t necessarily need to avoid all fruits and vegetables…sorry kids! Avoiding produce that are within the same category as the type of pollen you are allergic to may help. For instance, birch pollen is a big source of allergy cross-reactivity and kiwi, celery, nectarines, apricots, and apples are amongst the most common triggers. In addition, buying organic, washing diligently, and removing the skin from offending food may also do the trick! Cooking also changes the chemical composition such that foods aren’t mistaken for the true allergen.

Poison Ivy

Believe it or not, some people hardly react when exposed to poison ivy while others experience severe symptoms and a prolonged recovery. Why does this matter? Poison ivy is actually a member of the cashew family! So, if your child has had the unfortunate pleasure of being exposed to poison ivy, oak or sumac and was highly reactive, you may discover allergy cross-reactivity with cashews, mangos, and/or pistachios since they’re all within the same family.

The take-home message here is that if your child has a known allergy to any specific food or naturally occurring compound, it may be worth digging a little deeper. Becoming familiar with other items or foods that contain similar chemical structures or belong to the same family can help pinpoint culprits for ongoing behavioural, skin, and/or digestive issues. Your naturopathic doctor or healthcare practitioner can help guide you in the right direction when it comes to allergies and intolerances, and help you find ways to treat the less dangerous symptoms. Research is just beginning to unearth the far-reaching consequences of the allergic process but the good news is that it’s fairly easy to access information if you know what you're looking for!  

*Originally published April 14, 2016