The range of possible allergies is huge – whether pollen, grass, animal hair, food, cosmetics, medications or fragrances: When the immune system strikes out against these actually harmless environmental substances, it can lead to many different complaints: The eyes burn, the nose runs and itches, severe allergy sufferers even have problems breathing. To alleviate the symptoms of an allergy, often only renunciation and behavioral changes help. With certain allergies, however, hyposensitization can also lead to relief of the symptoms.
Course of an allergic reaction
When the immune system overreacts to contact with normally harmless substances by seeing them as enemies and producing antibodies as a result, an allergic reaction occurs the next time the person comes into contact with that substance. Antibodies such as immunoglobulin E cause the body’s own defense cells to release aggressive inflammatory substances. Histamine and other messenger substances then lead to swelling, itching and dilated blood vessels. This reaction can be localized or affect the entire body – depending on whether the nose, skin, bronchial tubes or circulatory system are affected. In addition to the reaction via antibodies, which often occurs minutes after contact with the “hostile” substance (the allergen), the immune system also has the ability to make certain cells (T cells) react to substances – this is how contact allergies work. Here, the reaction often occurs hours or days later.
Causes of allergy
Why the immune system suddenly reacts allergically is still unknown. Allergies are increasing worldwide – it is speculated whether, in addition to hereditary influences, increasing environmental pollution or too little contact with germs in childhood are responsible. A total of over 20000 allergy-causing substances are known: One can inhale them, ingest them with food or as medication, and have contact with them through the skin – even involuntarily as in a wasp sting. Differentiated from the allergic reaction is the pseudoallergy, which shows similar symptoms as an allergy, but already occurs at the first contact with a substance – without the body forming antibodies. For example, people often react pseudoallergically to salicylates (also to ASA). In cross-allergies, on the other hand, the body reacts to substances that have some similarity to the substance to which it has formed antibodies – for example, people with a birch pollen allergy often react to apples or nuts.
Typical symptoms of allergies
Allergy can be accompanied by a variety of symptoms: Swelling, itching, and dilated blood vessels cause redness and conjunctivitis on the eyes. On the nose, there may be rhinitis and a swollen nasal mucosa that impedes breathing. If the lungs also react, asthma develops: viscous mucus forms in the tense, swollen bronchial tubes, which can only be coughed up with difficulty. In addition, there is the typical humming, lowing asthma breathing sound. The skin of allergy sufferers often itches and tightens, and is also dry and red: in the area of these eczemas, the skin texture changes from delicate to coarse (particularly severe in the case of neurodermatitis). In addition, digestive problems with diarrhea, flatulence, constipation or bloating in the gastrointestinal tract are possible. In addition, the dilation of the blood vessels can lead to serious circulatory problems – if the blood virtually “pools” in a reaction that takes place throughout the body, cardiovascular failure occurs. This life-threatening situation is called anaphylactic shock, and often occurs in insect venom allergies or after intravenous administration of certain drugs.
Allergies: Diagnosis
Anamnesis (asking for medical history): all complaints can be further narrowed down by asking specific questions – nevertheless, allergy diagnostics often remains detective work. For example, a stuffy nose every morning can indicate a house dust allergy, and pets can also be blamed for many an allergy. Different substances are tested in various skin tests – redness, itching and a swelling indicate that the immune system is really reacting to the substance. Unfortunately, skin tests are not always reliable. Blood test: The concentration of immunoglobulin E in the blood indicates whether there is an allergy at all (RIST test), the more expensive RAST test confirms an allergy to a specific substance if the skin test was previously conspicuous.In a provocation test, the affected person is deliberately confronted with the possibly allergy-causing substance – because of the risk of a violent reaction (the anaphylactic shock), this is performed only rarely and under medical supervision.
