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Triggers of allergies and intolerances

An allergy is an excessive reaction of the immune system after repeated contact with substances that it recognizes as foreign and potentially dangerous, so-called allergens (usually proteins). The tendency to such a reaction is genetically inherited and can be triggered by various environmental influences.

Non-immunological intolerances (especially of food) are called intolerances. This occurs, among other things, when the body lacks a certain enzyme to break down a food or to transport it through the intestinal wall. Symptoms similar to those of intolerances can also occur if the small intestine is colonized with colon bacteria (DDFB, SIBO).

To find out whether you have an allergy, intolerance or intolerance to certain substances, ask your doctor to refer you for an allergy test at our Allergiezentrum.

Allergy triggers

Typical triggers of allergies

Pollen (tree, grass and weed pollen)

A pollen allergy is triggered by the smallest plant components in the air, the pollen. Pollen allergy is the most common form of allergy.

Pollen from trees (e.g. birch and ash) as well as shrubs, grasses and grains (e.g. rye), or even herbs (e.g. mugwort and ragweed) can trigger a pollen allergy.

As soon as the fine pollen comes into contact with the mucous membranes in the nose or eyes, a pollen allergy can be triggered. The body's own immune system reacts to the actually harmless tree, grass or herb pollen. Especially in spring and summer, when everything in nature begins to bloom, this manifests itself in itchy, red eyes, chronic runny nose, skin rashes and sometimes asthma. Patients who only experience symptoms in autumn must consider an allergy to herb pollen (e.g. mugwort and ragweed). Many allergy sufferers do not leave the house during the pollen season because the risk of being bothered by these pollen allergy symptoms is too high for many people.

However, you should not let your joy of life be taken away and instead take appropriate countermeasures. Many patients are helped by symptomatic therapy with eye/nose drops or antihistamine tablets. In many cases, specific immunotherapy (vaccination) can significantly alleviate symptoms.

You can find current information on pollen counts at www.pollenwarndienst.at

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Mold spores

Mold in the air can also trigger respiratory allergies. This is usually caused by the spores that are spread in the air.

The most common molds in the outdoor air are Alternaria and Cladosporium, while Penicillium and Aspergillus are more common indoors. Mold spores can trigger bronchial asthma as well as allergic rhinoconjunctivitis.

Indoors, mold remediation is the most important measure. Symptomatic therapy with eye/nose drops or antihistamine tablets can also help.

In selected cases, specific immunotherapy can also be helpful and necessary.

Current information on mold spores can be found at www.pollenwarndienst.at

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Mites (house dust mites, storage mites)

Sneezing fits, an itchy throat, red eyes: often it is not plant pollen that is the cause of the symptoms, but house dust mites.

House dust mites live mainly in warm, humid climates, so mattresses and bed linen as well as stuffed animals, carpets and curtains are popular places to stay. People with a mite allergy suffer mainly from chronic runny noses (especially at night and in the morning), skin rashes or asthma.

Measures to reduce the number of mites, such as new mattress covers, allergy-friendly bed linen, special vacuum cleaners, etc. can help. If you take all of these measures to heart, you can often sleep again without any symptoms. If the symptoms become more severe, medication (antihistamines or cortisone-containing nasal drops) can provide relief.

Specific immunotherapy (allergy vaccination) is often useful, because if left untreated, a house dust allergy can lead to persistent symptoms or even chronic asthma.

Whether it is mite remediation, symptomatic therapy or allergy vaccination, you can reserve an appointment online for a consultation with our specialists here.

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Food (e.g. milk, egg, gluten/wheat, soy, nuts)

Food allergies (e.g. to milk or eggs) are not uncommon, especially in infancy and early childhood. But allergic reactions to food also occur in adulthood.

Symptoms of a food allergy often appear on the skin in the form of a rash (urticaria), swelling (angioedema) or redness. Signs of an allergy can also be found in complaints of the gastrointestinal tract, such as diarrhea, abdominal pain, flatulence, nausea and vomiting.

If an allergy sufferer is hypersensitive, i.e. very small amounts of the allergen are enough to cause intense reactions, breathing difficulties or an allergic shock (anaphylaxis) can occur under bad circumstances.

If a food allergy to cow's milk or chicken egg protein occurs in early childhood, there is a good chance that it will disappear by school age. This is different if it is an allergy to tree nuts (e.g. hazelnuts, cashews, walnuts), peanuts or seeds (e.g. sesame), or if the allergy only begins in adulthood. In this case, the prognosis that the allergy will disappear again is rather poor. The same applies to celiac disease, a chronic inflammation in the small intestine as a reaction of the immune system to gluten (wheat, spelt, etc.).

An accurate diagnosis of a food allergy, the right therapeutic diet and the issuing and training of an emergency kit (usually contains an antihistamine, cortisone and an adrenaline pen) are therefore important, sometimes vital.

First, the doctor will try to find out in a conversation when the symptoms first appeared and thus filter out possible allergens. Using a diet diary can also help here. Then, targeted further diagnostics are carried out using the skin test (prick test, prick-to-prick test) and a blood test (determination of the specific IgE against certain foods). Sometimes component diagnostics (molecular diagnostics) are also helpful).

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Animal hair (e.g. cat, dog, horse)

In the case of animal hair allergies, those affected do not actually react directly to animal hair, but rather to certain proteins that are found in skin flakes, saliva or urine and that ultimately stick to the animal's hair. These particles are then released into the environment via the hair. This can lead to an allergic reaction in sensitized people.

In most cases, immediate separation from the animal is recommended as a measure for an animal hair allergy. However, for many pet owners, it is hard to imagine parting with their beloved pet. If the symptoms are not yet very advanced, other measures can be used to try to get the allergy under control. In selected cases, specific immunotherapy ("vaccination") can also be recommended.

Cat allergy is the most common animal hair allergy. The allergen (Fel d1) is not found directly on the hair, but is a protein that occurs in the cat's saliva and other body fluids. This protein is then transferred to the hair via the saliva and dries there. Current studies are currently investigating whether it is possible to vaccinate cats directly so that they produce less allergen.

Dog allergies are rarer. According to recent studies, there are no so-called hypoallergenic dog breeds that are suitable for allergy sufferers. However, the allergen content differs greatly from one animal to another. There are also special dog allergens (Can f5) that are only found in the male dog's prostate secretion and can be removed by castration.

Horse allergies are increasing overall. The allergen flies very far and can therefore cause symptoms even at a relatively great distance from a horse stable. However, the burden is greatest in stables. In addition to horse allergens, other allergen sources (e.g. house dust mites, mold spores, hay/grass pollen) can also be found here.

Rabbits and other rodents can also cause allergies. Here the allergen is found mainly in the urine. Newer, rarer allergies have been described against reptiles or their food (grasshoppers). You can also be allergic to birds (parrots, budgies).

The most effective therapy is still allergen avoidance, i.e. if you have an existing animal allergy, you should avoid these animals. In addition to symptomatic therapy (antihistamines, etc.), specific immunotherapy (“vaccination”) can also be recommended in selected cases.

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Insect poisons (e.g. bee, wasp)

For allergy sufferers, even a single sting from a bee or wasp can have serious consequences and, without prompt help and emergency treatment, can even become a deadly threat. As dangerous as an insect venom allergy is, it is also the type of allergy that can be treated very well.

The venom of bees and wasps (less often of bumblebees and hornets, much less often of mosquitoes, horseflies and ants) can trigger allergic reactions.

This can range from increased swelling in the area of ​​the sting (local reaction) to a nettle rash (urticaria) to swelling in the face and larynx and breathing difficulties. In the worst case, a life-threatening anaphylactic shock develops.

In principle, allergy testing makes no sense if no previous sting has occurred and no symptoms have been present. If someone develops severe allergic reactions to insect stings that go beyond a purely local skin reaction (e.g. rash, breathing difficulties, circulatory problems, etc.), then allergy testing is advisable. The consequence could be the issuing of an emergency kit (consisting of an antihistamine, cortisone and an adrenaline pen) or the start of allergen-specific immunotherapy (AIT). However, a purely positive allergy test (so-called sensitization) without previously experienced reactions to insect stings is not meaningful, as it does not allow a prognosis for the next sting. Even in the case of a purely local reaction (i.e. increased swelling in the area of ​​the sting site), testing is not necessary, as it does not represent an increased risk of a systemic reaction of the body (i.e. circulation, breathing, etc.) to the next sting (with or without a positive allergy test). If it is only a local reaction, purely local therapy (ointments) or the administration of an antihistamine is sufficient. Exceptions to this are patients with repeated strong local reactions and frequent stings that significantly limit their quality of life. In these cases, allergen-specific immunotherapy (AIT) can also be considered after a positive allergy test.

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Medications (e.g. antibiotics and painkillers)

Not all reactions to a medication are an allergy. You can book an appointment with one of our doctors online here.

Adverse reactions to medication occur relatively frequently. Only a small proportion of these are genuine allergic reactions. During the consultation with the doctor, it will be determined which medication was involved (please take the packaging of the medication with you or write down the name), whether this could have been a possible trigger for a reaction and whether further testing is useful or possible.

Not all medications can be tested! For example, blood tests are only available for a few medications (e.g. some antibiotics). Skin testing can also only be carried out for certain medications that are suitable for this purpose (e.g. penicillins, cephalosporins, local anesthetics).

The medication tests take place after an initial consultation at one (or more) separately scheduled appointments. Before the skin test, you should (if possible) not take any anti-allergic medication for 3 days, as this can prevent an allergic reaction and falsify the test result.

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Contact and occupational allergens (e.g. dyes, metals, fragrances)

A contact allergy is the triggering of an allergic reaction by the body when it comes into contact with a very specific material or substance, which is then referred to as a contact allergen.

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Typical triggers of intolerances

lactose intolerance

Lactose intolerance is an intolerance to milk sugar due to an enzyme deficiency. The symptoms are often abdominal pain, a feeling of fullness and diarrhea. The diagnosis is made using an H2 breath test.

In contrast to milk allergy, lactose intolerance is caused by the lack of a special enzyme (lactase). Lactose itself is not absorbed and then reaches the large intestine, where local bacteria break down the lactose. This creates intestinal gases and acids, which can lead to significant discomfort with abdominal pain, sometimes colic-like pain, flatulence and watery diarrhea.

A detailed medical history is crucial for the diagnosis. A food diary can be very helpful here. The diagnosis can be confirmed using the lactose tolerance test or the H2 breath test.

To find out whether you have an allergy or intolerance to certain substances, ask your doctor to refer you to a consultation at the allergy center. The doctor will then plan the necessary and appropriate tests with you.

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fructose malabsorption

Fructose malabsorption, also known as fruit sugar intolerance, is the body's reduced ability to absorb fruit sugar (fructose). Consuming foods containing fructose can then lead to abdominal cramps, bloating and diarrhea.

The cause of fructose malabsorption lies in a disruption of the GLUT-5 transport system, which in healthy people ensures the absorption of fructose from the small intestine. If absorption is disrupted, the fructose ingested with food reaches deeper parts of the intestine, where it is broken down by bacteria. This produces large amounts of hydrogen, carbon dioxide and short-chain fatty acids, which can lead to abdominal pain, flatulence and diarrhea.

Keeping a food diary followed by dietary advice can be a game-changer. Fructose malabsorption is diagnosed using an H2 breath test.

If you suffer from the rare form of congenital (hereditary) fructose intolerance (which is diagnosed in infancy), this test must not be carried out.

To find out whether you have an allergy or intolerance to certain substances, ask your doctor to refer you to a medical consultation at the allergy center. The doctor will then plan the necessary examinations that are useful for you together with you.

 

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sorbitol intolerance

Sorbitol is often used in the food industry as a sugar substitute. Sorbitol intolerance results in reduced absorption of sorbitol through the intestines into the blood. The unabsorbed sorbitol is broken down by bacteria in the intestines and leads to the production of hydrogen (H2). This can lead to abdominal pain, flatulence, a feeling of fullness and diarrhea.

Keeping a food diary followed by dietary advice can provide important clues as to whether sorbitol intolerance is present. Diagnosis is made using an H2 breath test.

To find out whether you have an allergy or intolerance to certain substances, ask your doctor to refer you to a consultation at the allergy center. The doctor will then plan the necessary and appropriate tests with you.

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Bacterial colonization of the small intestine (glucose test)

When there is bacterial overgrowth in the small intestine, bacteria that do not normally occur here accumulate in this area. As a result, food components are broken down prematurely by these bacteria and gases are produced. The typical symptoms are flatulence, diarrhea and weight loss.

Bacteria are also normally present in certain parts of the intestine. They perform an important role in digestion and immune defense. However, if the wrong intestinal bacteria are present in too large numbers in the wrong place in the intestine, symptoms can arise (bacterial overgrowth, SIBO = small intestinal bacterial overgrowth). Sugar (glucose) in particular is then broken down early by these bacteria and intestinal gases (e.g. hydrogen, H2) are produced. This can then lead to various symptoms, such as bloating, a feeling of fullness or diarrhea.

The medical history is often very unspecific. A specific food cannot always be identified. Therefore, diagnosis using an H2 breath test is important. If the test is positive, intestinal cleansing (usually antibiotics) can be carried out after consultation with a gastroenterologist.

It can often be important to rule out lactose intolerance or fructose malabsorption before glucose testing, which can also be a cause of bacterial overgrowth in the small intestine.

To find out whether you have an allergy or intolerance to certain substances, ask your doctor to refer you to a consultation at the allergy center. The doctor will then plan the necessary tests that are useful for you together with you.

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Histamine intolerance (diamine oxidase deficiency)

Histamine is a substance produced by the body and is present in many foods (e.g. wine, cheese, salami, canned food). Histamine intolerance occurs when a person reacts with an intolerance reaction to even small amounts of histamine ingested with food.

Foods that are produced by microorganisms are particularly rich in histamine. In the body, histamine is broken down by the enzyme diamine oxidase (DAO), among others. If there is an enzyme deficiency or a histamine/DAO imbalance, this is referred to as histamine intolerance.

Histamine intolerance can cause numerous different symptoms such as headaches, reddening and itching of the skin, feeling hot, tiredness, dizziness, cardiac arrhythmias and palpitations, breathing difficulties, a blocked or runny nose, or digestive problems (diarrhea, stomach pain, flatulence), headaches and skin rashes.

If you suffer from one or more of the symptoms typical of histamine intolerance, it is advisable to first keep a diet diary for about 2 weeks and discuss this with our nutrition team. In addition, a blood test can be helpful, which can determine the histamine concentration and DAO activity in the serum.

To find out whether you have an allergy or intolerance to certain substances, ask your doctor to refer you to a doctor's consultation at the allergy center. The doctor will then plan the necessary and useful examinations with you.

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