An allergy to one item/thing can also mean an allergy to others. For example someone who has a banana allergy also has a 1 in 10 chance of being allergic to latex gloves! Today we uncover some common and some unusual relationships to help keep you and those you care for safe.
Pile of fruit slices
If you know or care for someone who has an anaphylactic reaction to something, the chances are they know what it is and they do everything possible to avoid it. Occasionally, perhaps, the inevitable happens and they have an Epi-Pen or similar device to use. Yet it’s not so well know that they may also be at risk from other foods and other substances. As First Aid Instructors, we’ve always known of the possibility, but it took some research to dig up the facts for you – so here’s the simple version.

What are Cross Reactive Food Allergies?

When a person has an allergy to one thing, there’s a risk they may be allergic to other things too. Mostly we’re talking about food allergies, because they are commonest, but pollen and latex also turn up on the list of possible cross reactions. They’re not something that gets talked about a lot and not all people who have allergies know about these.

Why do Cross Reactive Food Allergies happen?

Normally a person who has an allergy (to eg: milk) isn’t allergic to the whole liquid we call ‘milk’. They are allergic to a very specific chemical in the milk. Common examples would be an allergy to a protein – in milk it’s usually the protein called casein.
These proteins are often similar or identical in different foods. If you think about it, you probably know peas and beans are part of the same plant family. They grow in a similar way, they come in pods, we shell them (or don’t) and eat them. They share lots of similar chemicals inside the peas/beans. Now depending on how awake you were at school, you may or may not know that peanuts are in the same plant family. And you know lots of people have peanut allergies. Bet you didn’t know they have a 1 in 20 chance of being allergic to peas.

Which Cross Reactive Food Allergies actually matter?

Allergy food

OK, enough with the science, you can read a lot more in the reference if you want. What actually matters? What’s going to cause problems for you or your family? Here’s the list we have found so far. Don’t assume it’s complete, but it’s the best we’ve come up with! If you can add more, please write in the comments section (with references if possible!) Some of them will be obvious, some not so much.

Your allergies: You might also react to: Chances of the reaction
A legume (eg: peanuts) Other legumes (peas, beans, lentils) 1 in 20 (5%)
A tree nut (eg: Walnut) Other tree nuts (hazel, brazil, cashew) 1 in 3 (37%)
A fish (salmon) Other fish (swordfish, sole) 1 in 2 (50%)
A shellfish (shrimp) Other shellfish (crabs, lobster) 1 in 1.5 (75%)
A grain (wheat) Other grains (barley, rye) 1 in 5 (20%)
Cow’s milk Beef (eg: a burger!) 1 in 10 (10%)
Cow’s milk Goat’s milk almost certain (92%)
Cow’s milk Horse milk 1 in 25 (4%)
Pollen (birch, ragweed, etc) Fruits & veggies (melon, apple, etc.) 1 in 2 (55%)
Peach Other rosaceae (apples, pears, plums, cherry) 1 in 2 (55%)
Mellon Fruit (bananas, avocado) almost certain (92%)
Latex Fruit (kiwi, banana, avocado) 1 in 3 (35%)
Fruit (kiwi, banana, avocado) Latex 1 in 10 (11%)

Extra notes to the allergies table

  • Got allergies to lentil or chickpea? Then your chances of reacting to peas, peanuts, etc. are very high.
  • Canned fish are less likely to cause allergies.
  • Mollusc allergies (eg: clams) vs. crustaceae (eg: crabs) is less likely to be a problem than mollusc-mollusc (eg: clam, muscle) or crustacea-crustacea (eg: crab, lobster)
  • If you’re allergic to one type of grain, consider getting tested & professional advice. It would be hard to exclude all grains from your life!
  • Rosaceae – peaches are the most likely to cause problems
  • Allergic to melons? Watch out for squash, pumpkins and other gourds
  • ‘Just’ allergic to latex? Beware of banana, kiwi, avocado, chestnuts. Allergic to latex and pollens as well – you have a good chance of being allergic to way more fruit.

Where you can read more about Cross Reactive Food Allergies?

This is based on “Clinical implications of cross-reactive food allergens” by Scott & Sicherer, J ALLERGY CLIN IMMUNOL, DECEMBER 2001, 881+
Check our article on anaphylaxis too!