What is meant by atopy? What is sensitisation or progression? Key terms commonly used in allergology.


Complete elimination of specific foods from the diet, for example. In allergology, abstinence also means avoiding contact with the allergen, by giving up, for instance, specific pets or plants.

Adrenaline prefilled syringe/Emergency kit

Patients with severe allergic reactions (anaphylactic shock) to, for example, insect venom or food, should always have with them an emergency kit with an adrenaline prefilled syringe and emergency tablets and should receive verbal and written instruction in their use. It is important to check handling and shelf life of the prefilled syringe regularly. When there is a sudden drop in blood pressure, adrenaline narrows the blood vessels in minutes, thereby stabilising the blood pressure and circulation. It also causes the muscles of the bronchi (airways) to relax, making it easier to breathe.


An allergen is an otherwise harmless substance that triggers an abnormal immune response. Allergens are typically proteins.

Allergic march

If allergic diseases start as early as infancy and childhood and then follow a characteristic pattern, this is known as the allergic march. The term refers to the fact that children predisposed to allergy “grow out” of an allergy as they get older only to then begin to suffer from another.


Overreaction of the immune system to foreign but otherwise harmless substances such as pollen, food and house dust mites.

Allergy card

This is issued by a doctor following a medical examination. The allergy card is available in German, French and Italian plus English.

Allergy test

If an allergy is suspected, an allergy test can be performed in a GP surgery or specialist allergy clinic to identify or rule out a specific allergen. Allergy tests can be divided into skin tests, blood tests and provocation (or challenge) tests.


Anamnesis is another term for a patient’s medical history. It is based on the medical information provided by the patient in the initial consultation with the doctor. It helps establish the diagnosis. The patient’s medical history is usually taken before or no later than during the medical examination.

Anaphylactic shock (anaphylaxis, allergic shock)

Sudden, rapid and severe allergic reactions with a drop in blood pressure, circulatory collapse, loss of consciousness and shock. The reactions can affect two or more organ systems, such as the skin and mucous membranes, the digestive tract, the respiratory tract and the cardiovascular system. Potentially life-threatening symptoms occur within seconds or minutes, rarely hours, of exposure to the allergy trigger or allergen.

Anti-allergic agent

Any medication that treats or at least relieves the symptoms of an allergy. This often means antihistamines.


These contain substances that weaken or neutralise the body’s own messenger histamine by blocking the histamine receptors and thus alleviating the symptoms of an allergy. Hence, they are also known as histamine receptor blockers. Antihistamines are administered in the form of drops or tablets for the treatment of allergies.

Asthma attack

In an asthma attack, the airways narrow so severely that it becomes hard to exhale. Sufferers feel as if they are not getting enough air, which can cause anxiety. Typical symptoms of an asthma attack are difficulty breathing, shortness of breath or chest tightness and dry cough.

Atopy (predisposition)

A personal or family predisposition to produce antibodies on contact with otherwise harmless substances and to have an allergic reaction to them. Atopy denotes the tendency to produce abnormally high levels of immunoglobulin E antibodies (IgE). Atopic disorders include asthma, atopic dermititis and allergic rhinitis with conjunctivitis with hay fever and house dust mite allergy.


Biologics are currently the most potent medicines available to inhibit inflammation and undesirable immune system processes. The biologics available for the treatment of atopic eczema, asthma and urticaria contain antibodies modelled after natural substances in the body and synthesised in the laboratory.


Any medication that widens the bronchi (airways) and which is used to treat or prevent bronchoconstriction, i.e. abnormal or pathological tightening of the muscles of the airways. This occurs in diseases such as asthma.


Bumblebees are larger, heavier and hairier than honeybees, but both belong to the same genus. A bumblebee's stinger has no barbs and does not get lodged in the skin. Bumblebees are very good-natured and only sting when they feel threatened. Attacks with bites and stings are rare but can trigger allergic reactions. Bumblebee and honeybee venom are similar.

Calcineurin inhibitors/immunomodulators

Active substances in medication that influence the immune system. They include the active substances tacrolimus and pimecrolimus, which are calcineurin inhibitors. They are used to treat atopic dermatitis and, in the form of an ointment or cream, are applied topically to the skin, where they have an anti-inflammatory effect and relieve itching.


A vital hormone (messenger substance) produced in the adrenal cortex in humans and mammals. This hormone regulates the uptake of sugar, influences fat and protein metabolism and bone formation, acts on the immune system and suppresses inflammatory reactions. Owing to their potent anti-inflammatory effect, cortisone products are primarily used for inflammatory diseases such as allergic diseases, asthma and skin diseases (e.g. atopic dermatitis and contact dermatitis).

Cross-reaction (cross allergy)

In a cross-reaction, the body is unable to distinguish similar proteins (allergens). As well as their first allergy, such as an allergy to birch pollen, allergy sufferers usually react suddenly to one or two foods and to a different pollen.

Desensitisation (specific immunotherapy, hyposensitisation)

Therapy which seeks to treat the cause of specific allergies such as pollen allergies, house dust mite allergy and animal and mould allergies. Desensitisation therapy should be recommended for severe insect venom allergies (bee and wasp venom) because it protects against life-threatening reactions. The allergens are injected under the skin or administered as tablets or drops in incremental doses. The aim is to accustom the body to the allergen and thus prevent as far as possible further allergic reactions.

Differential diagnosis

Consideration of other possible diagnoses that may explain the symptoms or medical findings.

Elimination diet

When an allergy to a specific food is suspected, the food is temporarily removed from the diet. This diet should be followed strictly for two to four weeks. If there has been no marked improvement in the symptoms by the end of this period, the suspected food can in all likelihood be ruled out as a trigger. If the sufferer becomes symptom-free on the diet, this points to the suspected allergen. A provocation test can be performed to confirm the diagnosis.

Encasings (mite-proof covers)

These are made of densely woven fabric and are used to cover mattresses, pillows and duvets in cases of house dust mite allergy. The house dust mites are unable to penetrate the fabric.


Enzymes are proteins that trigger biochemical reactions. Enzymes have important functions in the metabolism. These include controlling the greater part of digestion.

H2 (hydrogen) breath test

The H2 breath test is used to detect fructose or lactose intolerance. The H2 breath test is performed as follows: The fasting patient first ingests 25 g of fructose or lactose dissolved in water. The amount of hydrogen in the patient’s exhaled air is then measured every thirty minutes for at least two hours. The hydrogen content of the exhaled air indicates how well the fructose or lactose is broken down in the small intestine.


This is a vital, hormone-like substance. Normally, the enzyme diamine oxidase from the intestinal mucosa results in the rapid breakdown of histamine.

Histamine intolerance

Histamine is both produced by the body and ingested in food. In histamine intolerance, the histamine is not properly broken down. Mature cheese and both smoked fish and sausage are particularly high in histamine. Red wine also contains high amounts of histamine.


Hornet venom is comparable to that of the wasp. The sting is more painful because the stinger is longer and penetrates deeper. Hornets are very peaceful; stings are rare and rarely discussed in connection with allergies.


Collective term for different types of insects such as bees, bumblebees, wasps, hornets and ants. There are over 115,000 known species of Hymenoptera, around 11,500 of them in Europe alone. Hymenoptera can trigger allergies with their venomous stings, which can lead to anaphylaxis (anaphylactic shock). Ant venom allergy is extremely rare in our latitudes.

Immunoglobulin E (IgE), IgE antibodies

In immediate allergies, the most common form of allergy, the immune system forms antibodies - immunoglobulin E (IgE) - against otherwise harmless substances such as pollen, house dust mites, animal saliva, insect venom and specific foods.

Immunoglobulin G (IgG), IgG antibodies

IgG antibodies are an integral part of our immune system. Unlike IgE antibodies, IgG antibodies against commonly eaten foods indicate a normal immune response and are not classified as pathogenic in the sense of a food allergy or food intolerance. Dietary recommendations and therapeutic measures based on IgG levels should therefore not be considered. National and European allergology associations unanimously advise against IgG diagnostics with foods.

Immune response

Reaction of the immune system to foreign organisms or substances. The immune system can react to foreign pathogens (bacteria, viruses, fungi, parasites). If the stimulus is classified as harmless, it will no longer trigger a reaction in the future (immune tolerance). Substances from the environment that are harmless in themselves can, however, be mistakenly classified as dangerous and trigger a reaction (allergy).

Immunomodulators/calcineurin inhibitors

Active substances in medication that influence the immune system. They include the active substances tacrolimus and pimecrolimus, which are calcineurin inhibitors. They are used to treat atopic dermatitis and, in the form of an ointment or cream, are applied topically to the skin, where they have an anti-inflammatory effect and relieve itching.


Immunology is the study of the biological basis of the body's defence against pathogens and other foreign substances (toxins). In addition, there are disturbances and malfunctions of these defence mechanisms. There are different branches of immunology. Clinical immunology examines disorders of the immune system as they occur in allergies.


A substance that influences one or more chemical, biological or physical reactions in such a way that they are slowed down, inhibited or prevented.


In cases of malabsorption, the intestinal tract is unable to absorb enough nutrients into the bloodstream and lymph ducts due to a disorder.

Mast cells

Mast cells are defensive cells of the immune system and are present in the skin and mucous membranes throughout the body, close to blood vessels and in the organs. One of the substances they release is histamine, which increases vessel permeability and can result in blood plasma escaping into body tissues. This leads to angioedema or wheals, such as in allergic reactions.


Spread of allergic reactions from the upper respiratory tract (nose, throat) to the lower respiratory tract (bronchi, lungs); evolution from allergic rhinitis to asthma. Roughly a third of pollen allergy sufferers also develop asthma at some point. Desensitisation is recommended to prevent progression (see also allergy march).

Provocation test

This involves the application of a solution of the suspected allergen to the mucous membranes of the eyes and nose. The solution may also be inhaled. If a drug or food allergy is suspected, the allergen is taken by mouth.

Pseudoallergy (pseudoallergic reaction)

This intolerance reaction very closely resembles a classic (immediate) allergic reaction but without any immunological reaction being detectable in the blood. The most common triggers are medicines and food additives. "Pseudoallergens" are substances/mediators such as histamine, which do not affect the immune system.


If present, this means the body has built up a misdirected, specific immune response after first contact with a foreign substance (often an allergen). On renewed contact, an allergic reaction may ensue. Sensitisation can usually be detected by means of a skin test. Not every sensitisation will cause symptoms. If symptoms arise, for which an allergen is suspected as the cause but no sensitisation can be detected, this is referred to as intolerance. An allergy may only be assumed if sensitisation is followed by symptoms of the skin, gastrointestinal tract, respiratory tract or circulatory system.

Skin test

  • Prick test
    Allergen solutions are dropped onto the skin of the forearm or the back and pricked with a fine needle under the skin (prick test). If the allergen causes a reaction after 20 minutes similar to that following a mosquito bite, the test is positive.

  • Epicutaneous patch test
    Using adhesive panels containing many test patches, small amounts of different contact allergens are applied on the patient’s back. This allows simultaneous testing of on average 30 to 40 substances and of even up to 80 substances where necessary. The panels are removed after two days, and the patient’s back is examined for any reactions to the substances. This is repeated after a further one to three days. The development of local eczema under a test patch indicates an immune system reaction and the substance triggering the reaction is identified as a contact allergen.

Skin tests are routinely performed by trained personnel.


In allergology, triggers refer to factors that induce allergy symptoms. They are not allergens (proteins), but additives or irritants such as perfumes. Even the cold can act as a trigger.


Also known as hives or nettle rash. The skin swells (wheals develop) and reddens. In urticaria, wheals can form or disappear again within a matter of minutes.

Winter feet

The appearance of dry, itchy and scaly skin changes on the anterior part of the foot, primarily during the cold season and often in children aged between two and ten years. A specialist needs to carry out the differential diagnosis to distinguish the condition from other conditions such as athlete’s foot and contact allergy.