Allergies: recognising and preventing symptoms

An allergy is an excessive reaction of the immune system to environmental substances that are harmless in themselves. Medically speaking, it is usually an immediate-type reaction, in which specific antibodies are produced against a particular allergen. If the body comes into contact with this substance again, mast cells release mediators, which trigger the allergic reaction. In addition to pollen, food and insect venom allergies, contact and drug allergies, as well as atopic dermatitis and allergic asthma, are also classified as allergic conditions in the broader sense.

It is not yet fully understood why some people have allergic reactions whilst others do not. A family history of allergies significantly increases the risk of developing an allergy: if both parents have allergies, many children will also develop an allergy. Environmental factors such as air pollution, changes in dietary habits and the so-called hygiene hypothesis (insufficient exposure to microorganisms during childhood) also contribute to the body’s reaction.

Allergies often develop in stages: it is not uncommon for skin irritation or a food allergy to first appear during childhood or adolescence, followed later by hay fever or allergic asthma. In addition, so-called cross-allergies can develop, in which the immune system confuses proteins of different allergens that are structurally similar. For example, between birch pollen and certain types of fruit. Stress can also trigger or exacerbate symptoms.

The symptoms of an allergy depend heavily on the trigger and the organ affected. In most cases, the skin, mucous membranes or a single airway are affected; in severe cases, several organ systems may be affected simultaneously. Every symptom should be taken seriously and, if in doubt, a doctor should be consulted.

There are a number of allergies that can affect a person’s quality of life and lead to unpleasant symptoms. These include:

• Pollen allergies
• Food allergies (such as to dairy products or fish)
• Insect venom allergies
• Other allergies (such as to sunlight, animal hair and birds)

Pollen allergy (hay fever)

In the case of a pollen allergy, the body has an allergic reaction to certain grass, herb or tree pollens. Different types of pollen are in the air depending on the season, meaning that allergy sufferers experience symptoms at different times of the year. However, as many types of pollen remain in the air for a very long time, those affected often find themselves suffering from the associated symptoms for much of the year.

The parts of the body affected are the eyes, nose and the throat and pharynx. Typical symptoms include itchy, reddened eyes, a runny or blocked nose and frequent sneezing. In cases of more severe exposure, the symptoms can spread to the lower respiratory tract and lead to allergic asthma.

Food allergy

A food allergy usually manifests itself within a few minutes to hours after consuming certain foods, such as milk, fish, nuts or chicken eggs. This can cause redness, hives or itching in the mouth and throat, and in some cases swelling of the face. In cases of severe food allergies, symptoms may also affect the gastrointestinal tract.

Insect venom allergies

Excessive reactions to bee or wasp stings are characterised by severe swelling, pain extending well beyond the sting site, and occasionally breathing difficulties or circulatory problems. A sting in the mouth or throat is particularly dangerous, as the swelling there can obstruct the airway.

Other allergies

Other allergies may be triggered by, for example, sunlight, animal hair or house dust mites, and manifest as itchy blisters, skin redness or breathing difficulties. Certain medicines can also trigger allergies.

In rare, severe cases, any form of allergy can progress to anaphylactic shock. Anaphylactic shock is life-threatening and requires immediate emergency medical treatment.

The diagnostic process begins with a detailed discussion of symptoms, when they occur and possible triggers. This is followed by allergy tests, primarily the skin test:

In the so-called prick test, small amounts of suspected allergens are applied to the skin and lightly pricked. If redness or a wheal appears within a short time, this indicates sensitisation and the range of allergens can be further narrowed down.

This is supplemented by a blood test, which detects specific IgE antibodies against particular allergens.

If the results are inconclusive, a controlled provocation test may be carried out under medical supervision.

The field responsible for this is generally allergology and clinical immunology, a sub-speciality that focuses on the diagnosis and treatment of allergic diseases.

Treatment depends on the type and severity of the allergy. For food allergies, there is as yet no curative treatment; in such cases, consistently avoiding the trigger foods is the most effective approach.

Desensitisation

Desensitisation, or specific immunotherapy, has proven particularly effective for people with pollen allergies and those allergic to insect venoms. In this process, the immune system is gradually acclimatised to the allergen through its controlled administration.

The aim is to at least reduce the allergic reactions or even make them disappear completely. Such treatment usually takes several years. For insect venom allergies, however, there is also a rapid treatment procedure, which is usually carried out on an inpatient basis.

Medicines

The course of an allergy varies greatly from person to person: some symptoms remain stable for decades, others worsen, whilst others subside spontaneously in adulthood. Anyone who already has an allergy is at increased risk of developing further allergic reactions over the course of their life, such as cross-allergies to related allergens.

Even a single symptom can indicate the onset of sensitisation. An untreated allergic reaction can become more severe over time. It is almost impossible to prevent an allergy entirely; however, those who consistently avoid a known allergen and seek medical advice at an early stage to clarify their symptoms can often prevent more severe courses of the condition.

If an allergy is suspected, an allergology department or a specialist centre is the right place to go. Specialist doctors offer thorough diagnosis, individually tailored treatment plans, as well as advice on specific immunotherapy and emergency management.