Cross allergies are increasingly associated with hay fever .Those suffering from a pollen allergy not only have to do without spring walks – often a bite in an apple or eating a peanut can have serious consequences for allergy sufferers. Because with them the immune system reacts hypersensitively to foreign substances, the so-called allergens. Since some allergens, for example the allergens of pollen, with which some foods resemble each other, allergy sufferers may experience so-called cross allergies. Often it is certain types of fruit, vegetables or nuts that trigger such a cross allergy.

Hay fever: trigger of cross allergies

Hay fever is often referred to as pollen allergy because it is caused by pollen from grasses, trees or herbs. Depending on which substances cause the allergy , the intensity of the symptoms can vary seasonally:

  • Pollen levels are usually highest in the spring and summer months.
  • The first early bloomers awaken in February or March, including the alder and hazel.
  • In the further course of the year, allergy sufferers will primarily have problems with birch pollen .
  • The flowering period of the grass, on the other hand, typically extends from May to August, so that an allergy to rye or oats sometimes only becomes noticeable in the summer months.

Mugwort is one of the most allergenic substances. This weed can also cause very severe symptoms in small quantities.

Since the allergy can spread to the bronchi and trigger an allergic asthma there, all cases of hay fever should be treated professionally by the allergist. This should also check whether the hay fever is accompanied by a cross allergy.

What is a cross allergy?

The allergens of pollen and some foods are partially similar in their chemical structure. Since the immune system cannot always distinguish the individual substances from one another, pollen allergy sufferers are often sensitive to certain foods. This is known as “cross allergy” or “pollen-associated food allergy”.

However, cross allergies do not only occur in connection with hay fever – other allergies are also possible triggers.

Common forms of cross allergy

Which foods can cause discomfort depends on the type of allergy:

  • There is often a cross allergy between tree pollen and various types of fruit, vegetables, nuts and herbs.
  • Anyone who is allergic to birch pollen often shows complaints when eating stone and pome fruit (e.g. apple, pear, cherry, plum or peach), strawberries, tomatoes, hazelnuts or soy.
  • There is also a relationship between mugwort pollen and certain spices, such as caraway, pepper or anise, but also with vegetables such as bell pepper, celery, carrot or cucumber .
  • Allergies to grass pollen often cause hypersensitivity to other cereals as well as various types of fruit, vegetables, nuts and spices (e.g. rye, oats, melon, kiwi, peas, peanuts or peppermint).
  • Allergies to house dust are often accompanied by a cross reaction to shellfish or crustaceans.
  • Cross-reactions between similar foods are also possible, for example between different types of nuts, cereals or fish.
  • Allergy to penicillin can lead to a cross allergy to a certain group of antibiotics.

There is also a link between contact and food allergens. A typical example of a contact allergy is latex allergy. This type of allergy is often accompanied by an allergy to nuts , fruit (e.g. avocado, banana or kiwi) or vegetables (e.g. potato, celery or tomato).


How does a cross allergy show up?

The symptoms of cross allergy usually appear immediately after eating and are usually local to the mouth area.

The following symptoms can occur, for example:

  • Swelling, tingling or itching of the oral mucosa
  • Blistering of the lips
  • Redness of the skin around the mouth

The allergy rarely affects the entire body. In these cases, the following symptoms may occur:

  • Quaddelbildungen
  • Gastrointestinal complaints
  • Circulation problems
  • difficulty in breathing

In the worst case, there is a risk of circulatory collapse, acute shortness of breath or even a life-threatening allergic shock.

Treatment of cross allergy with antihistamines

Medications can relieve the symptoms of a cross allergy. Antihistamines, for example, reduce the effects of the body’s own messenger histamine. In the case of an allergic reaction, this is released to a high degree and triggers the typical symptoms.

Depending on the active ingredient, antihistamines are available as nasal sprays, eye drops, tablets, syrups or drops. They not only alleviate the symptoms of cross allergy, but are also used against hay fever . Occasionally, however, they can cause fatigue as a side effect.

Hyposensitization for cross allergies

Only the so-called hyposensitization can combat the cause of a cross allergy sustainably . The aim of this treatment is to gradually get the immune system used to the allergens. The specific allergen is administered to the patient at regular intervals for several years, usually via an injection. The dose is increased over time.

Although this form of therapy is lengthy, it can counteract the cause of allergy as the only known method. Treatment can improve the symptoms or even completely alleviate the allergy. At least the quality of life of those affected is noticeably improved.

Hyposensitization can be done in both adults and children. This form of therapy is particularly recommended for patients suffering from hay fever. Fall is the best time of year to start treatment as the general pollen count is low at this time.

In the case of serious illnesses, such as asthma, this type of treatment should be avoided.

Do foods have to be avoided?

In the case of a cross allergy, completely avoiding the allergy-causing foods is the safest option to avoid the occurrence of symptoms – because even small traces of the allergen can sometimes trigger severe symptoms. However, many foods can also be made compatible by heating or freezing for a long time.

Fruit and vegetables in particular can be “made harmless” by heating. Also in the form of mus, juice , jam or cake, many types of fruit, such as the apple, are generally also compatible for allergy sufferers.

Other allergens, however, are heat-resistant. This is especially true for nuts, celery, fish, soy and many other animal products. In the event of an allergy, these foods should be avoided entirely.

The complaints often arise when eating the food, especially when the pollen in question is just flying. In this case, a seasonal waiver of the respective foods can be useful.

Always keep an eye on the cross allergy

As an allergy sufferer, you should pay attention to which foods you eat. The focus is always on the ingredients. With finished products in particular, it is sometimes necessary to read the ingredients very carefully: for example, soy can hide behind terms such as “vegetable oil” or “emulator lecithin”.

In order to find alternatives to the allergy-causing foods, it is advisable to draw up a nutritional plan together with a nutritionist. This procedure is particularly advisable if certain foods should be avoided entirely in order to prevent malnutrition .

In addition, allergy sufferers should be examined by the allergist at regular intervals. Food allergies can become weaker or disappear entirely over time. An allergy test can be used to determine whether the allergy is still active.

Keeping a food diary can also provide information about which foods could be harmful.

Always with you: the emergency kit

If an allergy has been confirmed or serious reactions have already occurred, it is advisable to carry an emergency kit with you. This includes antihistamines, cortisone and an adrenaline spray.

In the event of a so-called allergic shock, in which those affected experience a life-threatening state of shock, the medication contained in the emergency kit should be administered immediately after calling the emergency doctor.

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