Cross allergies

Hardly a patient who suffers from hay fever when the birches let their pollen fly understands why he or she could not tolerate the Christmas hazelnuts. Or why the lip or palate tickles after eating an apple. But everything could be related to hay fever, even if it sounds far-fetched.

Such cross-allergies can be found in about 60% of allergy sufferers. They range from itching through a furry feeling in the mouth to severe anaphylactic reactions.

The classic example of this is birch pollen allergy and concomitant intolerance to apples or hazelnuts.

Thus also an allergic shock or a severe asthma attack can be triggered by a cross-allergy. Mostly, only raw foods are not tolerated. When the apples are cooked, there is usually no problem anymore. Hardly anyone who is allergic to mugwort reckons that he or she cannot tolerate curry powder.

The cause of the cross-allergy is the fact that the allergy-causing substances, called allergens, have a structure very similar to that of some pollen and certain foods. This means the person responds "crosswise", because the similar proteins trigger the same reaction in the body – just at a different organ. Under certain circumstances, cross-allergy can be life threatening!

Therefore, many people with eczema or hay fever show allergic reactions to various foods, too. The reason for these so-called cross-allergies is the similarity of the molecular structure of food allergens and the allergens in the respiratory tract (e.g. pollen) or on the skin (e.g. mites).



Cross-reactive allergens

House dust mite

partial: red tree spider, storage mite

Birch pollen

Alder, hazel, beech pollen (copper beech); fresh fruit (pome and stone fruit such as apples, peaches, cherries); nuts, especially hazelnuts even in processed form (chocolate, cake, etc.); carrots; raw tomatoes

Grass pollen

Peanuts (legumes), soybeans, raw potatoes

Mugwort pollen

Herbs (e.g. chamomile), spice mixtures, celery, carrots, euonymus wood

Lilac pollen

Ash pollen (partially)

Ragweed pollen


Gelatine (gummy bears etc.)

Modified gelatine


Walnut, avocado, banana

possibly ovalbumin
(major allergen of the hen's egg)

Bird feathers such as down feathers, etc.

What can you do?

The important thing is, first of all, to avoid all allergens! This is often easier said than done. Here are a few tips for this:

  • Replace intolerable fresh herbs with dried ones
  • In case of allergic reactions to apples or pears, experiment with different varieties
  • Replace raw fruits or vegetables with cooked one
  • Prefer berries to pome or stone fruit (raspberries, currants, blueberries, blackberries)
  • Prevent the risk of allergies by a varied diet

A normally responsive immune system fights intruders such as viruses, bacteria, fungi as well as other foreign substances in most cases without pathological reactions. Substances identified as harmless are essentially ignored. By contrast, an overzealous immune system reacts to such harmless substances with unreasonable violence – an allergic reaction. This is due mostly to increased permeability of the intestinal mucosa.

A functioning immune system can be achieved, however, only when the intestinal mucosa is intact. Allergic diseases can be improved via therapy of the mucous membranes with Synerga®!

Please note, however, that this information does not replace a detailed discussion with your doctor. Some information may also cause unnecessary fears. Please talk to your doctor about such concerns. And we explicitly encourage you to ask your doctor your questions, even very personal questions that cannot be answered by this information.

Please read the patient information leaflet carefully. If you have any further questions after reading it, please ask your doctor or pharmacist.