Cross Allergy

In people with grass pollen allergy, antibodies are formed against certain components (antigens) of the pollen. If these antibodies also recognize antigens from tomatoes due to structural similarity and then trigger an allergic reaction, this is called a cross-allergy. If someone suffers from a cross-allergy, he or she is not primarily allergic to tomatoes, but suffers the typical symptoms of an allergy due to his or her pollen allergy.

Often there are several cross-allergies, such as to apples or peanuts. There is a variety of different foods that can be affected, but not necessarily! Whether this is the case for you personally can either be clarified by an allergy test or is noticeable by the reaction after ingestion of the food by appropriate symptomatology.

Diagnosis

The diagnosis of histamine intolerance is usually made as an exclusion diagnosis based on the clinical picture. The repeated occurrence of symptoms after consumption of tomatoes or other histamine-containing foods in the absence of any other explanation makes the diagnosis likely. A dietary trial over two weeks, in which histamine-containing food is completely avoided, can help to establish the diagnosis, as no symptoms should occur during this time.

In addition, the histamine level and the amount of the histamine-degrading enzyme in the blood before and after the discharge test can be compared to establish the diagnosis. Since there is unfortunately no reliable test for making a diagnosis, the diagnosis is often wrongly made because no other reason has been found.A cross-allergy is also determined primarily by observation of the symptoms, but an allergy test to determine the underlying allergy, for example the prick test, is always part of the diagnosis. You can find additional information on our page on testing for food allergies

Associated symptoms

In addition to the itchy red skin rash, there may also be increased burning or redness with itching in the mouth and throat area. Headaches and dizziness as well as gastrointestinal complaints such as diarrhea, nausea and vomiting may also occur in some cases. In addition, there may be deviations in blood pressure in the sense of an increase above normal levels or a drop.

The occurrence of joint pain and water retention is also possible. Especially in the case of cross-allergies with pollen, allergic asthma can also occur in the form of severe breathing difficulties. If swellings in the throat area occur, a doctor should be consulted as soon as possible, as the intolerance can lead to life-threatening breathing difficulties. A condition with severe circulatory problems is also an urgent indication for a visit to a doctor.