Explore cross-reactive relationships between 14 major allergen groups. Select your known allergies to see which other foods may pose a risk, with probability percentages and the responsible protein families.
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Select Your Known Allergies
Click on one or more allergen groups below that you are allergic to. The tool will display cross-reactive foods, probability of reaction, and the shared protein responsible.
Cross-Reactivity Assessment
Ingredient Safety Checker
Type a food or ingredient to check if it cross-reacts with any of your selected allergies above.
Understanding Food Allergen Cross-Reactivity
Food allergen cross-reactivity is one of the most important yet frequently misunderstood aspects of food allergy management. When your immune system develops an allergy to a specific food protein, it creates antibodies that recognize the three-dimensional structure of that protein. If another food contains a protein with a similar structure, those same antibodies may bind to it and trigger an allergic reaction, even though you have never been exposed to that food before. This phenomenon has significant implications for dietary management, and understanding the science behind it can help you make safer food choices while avoiding unnecessarily restrictive diets.
The Major Cross-Reactive Allergen Families
Several protein families are responsible for most food allergen cross-reactivity. Tropomyosin is a muscle protein found in crustaceans, mollusks, and dust mites that accounts for the high cross-reactivity between shrimp, crab, lobster, and other shellfish. The clinical cross-reactivity within crustaceans is estimated at 75 percent, meaning three out of four people allergic to one crustacean will react to another. Cross-reactivity between crustaceans and mollusks (like clams and mussels) is lower, around 30 to 40 percent, because their tropomyosin structures are more divergent. Caseins are the primary milk proteins responsible for cross-reactivity between cow, goat, sheep, and buffalo milk, with rates exceeding 90 percent. Legume storage proteins called vicilins and legumins are shared across peanuts, soybeans, lentils, and other legumes, though clinical cross-reactivity is lower than lab testing suggests, typically 5 to 10 percent for peanut to other legumes.
Pollen-Food Allergy Syndrome
One of the most common forms of cross-reactivity is pollen-food allergy syndrome, previously called oral allergy syndrome. This affects up to 70 percent of people with birch pollen allergy, who may experience itching and tingling when eating raw apples, pears, cherries, peaches, plums, carrots, celery, hazelnuts, and almonds. The cross-reactive proteins in these foods, called pathogenesis-related proteins (PR-10), share structural homology with Bet v 1, the major birch pollen allergen. Because these proteins are heat-labile, meaning they break down when cooked, most people with oral allergy syndrome can eat the same foods when they are heated, baked, or canned. Grass pollen allergy cross-reacts with tomatoes, potatoes, and melons through profilin proteins. Mugwort pollen cross-reacts with celery, carrots, and spices through lipid transfer proteins.
Tree Nut Cross-Reactivity
Tree nut allergy presents a complex cross-reactivity picture because the term encompasses botanically diverse species. Walnut and pecan are closely related (both Juglandaceae family) with cross-reactivity rates of 80 to 90 percent. Cashew and pistachio (Anacardiaceae family) show similarly high cross-reactivity of 70 to 80 percent. However, cross-reactivity between walnut and cashew is much lower, around 20 to 30 percent. Almonds, which are technically stone fruits related to peaches, have moderate cross-reactivity with other tree nuts at 15 to 30 percent. Many allergists now recommend component-resolved diagnostic testing to identify which specific nut proteins a patient is sensitized to, enabling targeted avoidance rather than blanket tree nut elimination. This approach significantly improves quality of life for people who may safely consume most tree nuts while needing to avoid only one or two.
Latex-Fruit Syndrome
Approximately 30 to 50 percent of people with latex allergy also react to certain fruits and vegetables, a condition called latex-fruit syndrome. The cross-reactive proteins include chitinases and hevein-like proteins. The highest-risk foods are banana (50 percent cross-reactivity with latex), avocado (35 percent), chestnut (30 percent), and kiwi (25 percent). Moderate-risk foods include potato, tomato, bell pepper, and papaya. This cross-reactivity is clinically important for healthcare workers and others with occupational latex exposure who may develop progressive food allergies.
Important Limitations and Medical Disclaimer
This tool provides educational information about food allergen cross-reactivity based on published clinical research and review articles. Cross-reactivity percentages represent population-level probabilities and may not reflect your individual risk. Many factors influence whether a cross-reactive food will actually cause a reaction in a specific person, including the specific protein epitopes involved, the amount consumed, whether the food is cooked or raw, and individual immune system variations. Laboratory cross-reactivity (IgE binding in blood tests) is consistently higher than clinical cross-reactivity (actual symptoms upon eating), meaning blood tests overestimate real-world reaction rates. This tool is not a substitute for professional medical advice. Always consult with a board-certified allergist before introducing potentially cross-reactive foods into your diet, and carry prescribed emergency medication if you have a history of anaphylaxis.
⚖ Lab vs. Clinical
Blood test cross-reactivity rates are 2-3x higher than clinical reaction rates. Positive IgE tests do not always mean you will react to the food when eaten.
⚖ Cooking Changes Risk
Many cross-reactive proteins in fruits and vegetables are heat-sensitive. Oral allergy syndrome symptoms often disappear when the food is cooked, baked, or canned.
⚖ Test, Don't Guess
Component-resolved diagnostics can identify exactly which proteins trigger your allergy, enabling targeted avoidance rather than eliminating entire food groups.
⚖ Carry Epinephrine
If you have a history of anaphylaxis, always carry prescribed auto-injectors when trying foods that may cross-react with your known allergens.