Cross Allergy – Causes, Symptoms & Treatment

Kreuz allergy

When you bite into an apple or an apricot, your mouth suddenly starts to itch. Shortness of breath is noticeable after the chocolate cake. These signs indicate a cross allergy . But what exactly is it all about?

What is a cross allergy?

cross-allergy always occurs when another allergy is already present. The symptoms of cross allergy can be similar to those of pollen allergy .

Sneezing fits, watery eyes, itchy rashes and shortness of breath. However, since the allergen enters the body when you eat and is not only absorbed through the air like pollen, a cross-allergy can also become dangerous. Swelling of the mouth or windpipe can cause suffocation.

In the worst case, an anaphylactic shock can occur with a cross-allergy. This state of shock is life-threatening and requires emergency medical care.


The causes of cross-allergies are clear: the patient has an allergy and now reacts to other substances. A cross allergy has developed. The reason: Due to the similarity in the structures of certain allergens, the patient suddenly reacts to foods that were previously well tolerated.

A cross-allergy is very common in pollen allergy sufferers. Almost half of those allergic to birch pollen also react to stone fruit, soy , celery and nuts. People who are allergic to grass pollen can develop cross-allergies to peanuts, potatoes, grains, soybeans and tomatoes. Even with an allergy to house dust mites , a cross-allergy can easily develop. Suddenly those affected can no longer tolerate marine animals.

Sometimes it is enough if, in the case of a cross-allergy, the threatening foods are simply removed from the dining table during the pollen season. But sometimes only a consistent and decades-long renunciation helps.

Symptoms, Ailments & Signs

The cross allergy can manifest itself in different symptoms. They depend on the one hand on the main allergen and on the other hand on the way in which the allergenic substance comes into contact with the patient. In this context, contact with the skin, contact with the mucous membrane of the mouth, nose and throat, with the respiratory tract and the gastrointestinal tract come into question.

In this context, the symptoms of the cross-allergy are not always the same as those of the main allergy. While the birch pollen allergy is one of the allergies that irritate the mucous stimuli and cause itching of the eyes as well as a runny nose, the cross-allergy to apples or nuts can be recognized by tingling and swelling in the mouth and throat area.

Symptoms in the area of ​​the mucous membranes can affect the eyes, nose, throat and respiratory tract in general. Allergic conjunctivitis ( conjunctivitis ) of the eyes manifests itself with itching, redness and swelling. The mucous membranes of the nose react with secretions and sneezing attacks occur. An allergic cough is also possible. A complication that can occur with almost all cross-allergies is anaphylactic shock with shortness of breath and loss of consciousness .

Allergens that get into the mouth with food cause tingling and swelling there and can become evident in the further course of digestion with gastrointestinal complaints. Allergens that react to skin contact are contact allergens. Here the skin forms itchy, sometimes weeping wheals .

Diagnosis & History

The suspicion of a cross-allergy must be confirmed by the doctor. If allergic symptoms have occurred, the allergist will examine the blood to detect any allergens. In an interview, he will discuss the further procedure with the patient.

In addition, the doctor will provide information about all those allergens that can also trigger a cross-allergy. If there is only an allergy to pollen and no cross-allergy has yet occurred, those high-risk allergens should be avoided or at least their consumption should be restricted as a precautionary measure.

The ingredients of finished products should also be read carefully. Because in the case of a cross-allergy, even the smallest traces are enough to trigger an allergic reaction.


Since the allergic reaction in a cross-allergy is basically the same as in a normal allergy, the cross-allergy can lead to just as serious consequences as any other allergy. Cross allergies can lead to different symptoms depending on the severity. If the cross-allergy exists, for example, in addition to a pollen allergy in the form of a food allergy, complaints in the mouth and throat area, but also in the gastrointestinal tract, can be expected when certain foods are eaten.

Severe symptoms of a cross allergy can be very dangerous. As with general allergies, cross-allergies can lead to serious complications, such as allergic shock. Allergic shock as a life-threatening complication can lead to impaired blood circulation and, in extreme cases, to cardiac arrest. Because allergic shock is an emergency, it must be treated by a doctor with medication or CPR for cardiac arrest.

Another complication is shortness of breath, which can occur with both the original allergy and the cross allergy. The allergic reaction can cause the mucous membranes in the larynx, trachea and bronchi to swell. A narrowing of the inner cross-section impedes the flow of air, resulting in shortness of breath. If contact with the allergen in question can be avoided, the occurrence of possible complications can be minimized.

When should you go to the doctor?

Those affected who suffer from an allergic reaction should always seek detailed information from a doctor about possible cross-allergies. As soon as the presence of an allergy has been confirmed by medical tests, extensive information is required about cross-links to other allergic triggers. If you still experience watery eyes, itchy skin or discolouration of the skin after eating food, you should consult a doctor. A runny nose, reddening of the eyes or a sore throat immediately after eating are further indications of an intolerance.

A doctor must be consulted for medical treatment. The sudden and rapid emergence of pustules and poplars on the skin indicates irregularities that should be examined. If you experience tightness in your throat or shortness of breath, consult a doctor as soon as possible. If you stop breathing, feel suffocated, or lose your ability to breathe, call an ambulance. People who are experiencing severe anxiety or panic attacks due to reduced ability to breathe need immediate medical attention. If the person concerned experiences an anaphylactic shock, his life is in danger. An ambulance must be called and first aid measures must be initiated immediately by those present to ensure survival.

Treatment & Therapy

If a cross-allergy and the pollen or house dust mite allergy associated with it remain untreated, there is a risk that the symptoms will worsen. A gradual shift from watery eyes and sneezing fits to shortness of breath, skin reactions and even circulatory collapse takes place.

If the dreaded anaphylactic shock occurs, a cross-allergy can even lead to death if left untreated. Treating a cross-allergy begins by identifying the original allergy. If this allergy is combated, the cross-allergy often disappears as well. If an allergy remains untreated, there is a risk of further allergies and cross-allergies. The lives of those affected are becoming increasingly restricted.

In the first place, the allergens should be avoided. This includes all foods associated with the cross-allergy. Medications are used to alleviate the symptoms. Acupuncture , autohemotherapy, the consumption of black cumin oil, nettle tea or homeopathic globules have already led to many a cure. However, these alternative forms of treatment do not help all patients.

Conventional medicine recommends desensitization. Here the smallest amounts of the allergen are injected under the patient’s skin. Once the pollen allergy has been treated, the cross-allergy to the food often improves as well.

Outlook & Forecast

There are testimonials from those affected in whom allergies and thus also cross-allergies have grown together, in which they suddenly disappeared. This is not the norm. Those who manage to consistently avoid the allergen have the best prognosis of not suffering any health damage from a cross-allergy. If this is possible, there is usually no further allergic reaction that could be considered hazardous to health.

Since consistent avoidance of an allergen is not always possible, desensitization also has a good prognosis for many of those affected. Anyone who attends all appointments where weakened pathogens are injected for increasing desensitization has a good chance of suffering no or at least only weakened allergic reactions.

When this is also not possible, sufferers have to live with drugs that are given as needed to interrupt the allergic reactions caused by the cross-allergy. Today’s drugs are very safe and so well tolerated that children can usually be treated well with them. If the medication is taken as prescribed by the doctor, the prognosis is good that the cross-allergy can be brought under control.


cross allergy cannot always be prevented. However, it is important to avoid allergy triggers. Indoor mold should be eliminated. Tobacco smoke is also harmful to the body. A mother should exclusively breastfeed her child for at least six months to reduce the risk of allergies.

If an allergy is already present, certain foods should be consumed with caution. These include nuts (hazel pollen allergy), stone fruits, carrots, celery (birch pollen allergy), spices (mugwort allergy) and tomato, kiwi, melon (grass pollen allergy).


The question of aftercare depends on the success of the initial therapy. In principle, there is a chance of healing with the help of hyposensitization. If this is successful, no follow-up care is necessary. The recurrence of the cross allergy is excluded. In all other cases, the disease persists.

Aftercare aims to avoid acute contact with allergens and to train the patient for his everyday life. This happens in a conversation. Scheduled follow-up examinations, such as those known from tumor diseases, are not planned. The person concerned therefore has a high degree of personal responsibility. When preparing food, certain foods should be avoided or prepared in such a way that no intolerance arises.

Nutritional advice promises long-term freedom from symptoms. The prevention of complications is also a mainstay of aftercare. It can always happen that carelessness causes an allergic reaction. In this case, the patient must know how to behave. He will be informed about this as part of the initial diagnosis. As standard, those affected should have an allergy pass and an emergency bag with medication with them. However, these measures are only suggested by doctors. It is up to the patient to implement it themselves.

You can do that yourself

If there is a cross allergy, there are some helpful tips that allergy sufferers can use to make everyday life easier. The preparation can help with allergic reactions to fruit or vegetables. Instead of raw apples or cherries, cooked alternatives such as apple or cherry pie or apple compote can be more tolerable. Cooked carrots are also better tolerated. Individual varieties often make the difference.

Avoiding alcohol as much as possible can also be very helpful for allergy sufferers, as alcohol can intensify the allergic reaction. The same applies to stress . It is therefore important to avoid possible stressful situations and burdens in everyday life. When it comes to nutrition , individual nutritional advice is recommended in order to find possible alternatives to food.

Medicines basically help to alleviate the various symptoms of an allergy. These can be tablets, inhalation sprays, creams or ointments or injections. A balanced diet is also important, as is avoiding the allergen. In the event of severe allergic reactions, those affected and those around them should be informed about how to deal with severe circulatory problems in the event of an allergic reaction. This includes an allergy pass and an allergy emergency kit with the appropriate medication. Physical activity and a healthy lifestyle can reduce allergies and reduce symptoms.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.