What is Cross-Reactivity?

Allergies can be caused by a variety of factors. These could vary from animal products, mites, molds, latex, pollen, medicines, plants, venom, as well as food. Most of the non-food related allergies can be accompanied by reactions in the mouth or the gastrointestinal tract.  Food related allergies, on the other hand, can be accompanied by several symptoms including: skin itching, hives, swelling of the skin, nausea, vomiting, diarrhea, breathing difficulties, or anaphylaxis.

In patients with allergies, the best treatment is commonly prevention. Determine the allergen trigger, and avoid it. Be cautious of similar allergen sources as cross-reactive symptoms may occur.

What is a Cross-Reactive Allergy?

Cross-reactivity allergy occurs when the antibodies against a specific allergen identify other allergens from other sources, thus inducing an allergic reaction to those allergens, as well. Cross-reactions are most commonly seen between certain pollen types and foods. Some individuals with pollen allergies can develop symptoms around and in the mouth and throat immediately after consuming raw fresh fruits, vegetables, nuts or seeds that contain proteins cross-reactive to the pollens.

For example, some people who are allergic to birch pollen may not tolerate raw apples, peaches, pitted fruits, carrot, peanut or hazelnut as well. Antibodies targeting a birch pollen allergen may detect a similar protein in these fruits and vegetables. As a result, the people suffering from birch pollen allergy may react to the consumption of the above by means of swelling, itching and redness.

Cooked forms of the foods are usually tolerated because the food proteins that are pollen cross-reactive are broken down when subjected to heat. The following list contains a selection of cross-reactive allergens.

Common cross-reactive allergies between pollen and food:

  • Birch pollen: apple, carrot, celery, pear, tomato, cherry, tree nuts
  • Goosefoot pollen: banana, melon, peach
  • Mugwort pollen (weed): carrot, celery, aniseed, peach
  • Ragweed pollen: melon, cucumber, banana, sunflower
  • Timothy grass: apple, lychee, tomato, celery, corn, bell pepper, paprika

Common cross-reactive allergies between different foods:

  • Shellfish: high degree of cross-reactivity among crustacean shellfish (shrimp, lobster, crab, crawfish). The risk of allergy to another crustacean shellfish is 75%. The risk may be lower for cross-reactivity between crustacean shellfish and non-crustacean shellfish (clam, oyster, scallop, mussels).
  • Peanuts and Soybean: The risk of allergy to another legume (soy, other beans) is more than 50%, as seen in skin tests. However, 95% of people who react positive can tolerate and eat the cross-reactive legumes.
  • Tree Nut: Walnut, hazelnut, Brazil nut, pecan, pistachio, cashew
  • Cow’s Milk: The risk of allergy to another mammal’s milk such as goat and sheep is high.
  • Fish: This covers various different species of fish, including fresh and salt water fish. The risk of allergy to other fish when an individual is allergic to one fish is about 50%.

Common cross-reactive allergies between latex and food:

Latex is a natural product that comes from rubber trees and is processed to make balloons, waistbands on clothing, rubber bands, condoms, and other products. The allergy is a reaction to certain proteins in latex that your body mistakes for harmful substances. Symptoms can vary, but the most concerning type is an IgE-mediated allergic reaction to latex that results in immediate hives, swelling, wheezing and anaphylaxis. While the overall prevalence of IgE-mediated reactions to latex is rare, about 30 to 50% of people in this group can experience symptoms with any or several cross-reactive fruits such as banana, avocado, kiwi and chestnut.

Schedule a Consultation

Individual reactions vary when it comes to cross-reactivity allergies. Because of the challenges in diagnostic testing posed by allergen cross-reactivity, it is important to talk with a doctor about your symptoms with foods. Your medical professional has expertise in the area of allergen cross-reactivity and can help make an accurate diagnosis and provide guidance as to whether a cross-reactive food needs to be avoided or not.

If you suspect cross-reactivity as an underlying condition to your symptoms, it may be time to discuss a prevention and treatment plan with your doctor. Join our many satisfied patients, and schedule an appointment with Dr. Shukla today, and learn how to live an allergen-free life.

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