How does hyposensitisation help allergies?

Besides avoiding allergens, allergy management includes treating patients with medication and hyposensitising them to the allergy trigger. This involves administering gradually increasing doses of the allergen to increase the patients' tolerance.

Long-term data has confirmed the effectiveness of this treatment along with its ability to prevent the development of allergic bronchial asthma. Hyposensitisation (also known as allergen-specific immunotherapy) therefore not only alleviates symptoms but also helps prevent asthma.

This type of treatment is used when extensive diagnostic procedures have clearly identified the allergen (or groups of allergens) that triggers the allergy, but the allergen cannot be avoided (abstained from) and there is evidence that this particular allergy can be successfully treated with hyposensitisation.

How is the patient immunised?

The intervals at which injections, drops or pills are administered can vary depending on the treatment plan. The classic form of treatment begins with a low dose of the allergen, which increases as the treatment progresses. The dosage must be adjusted depending on the patient's individual degree of tolerance and current state of health.

Classic form

During the build-up phase, the patient receives weekly injections with increasing concentrations of the allergen. Once the maintenance dose has been reached, the patient receives one injection a month. The treatment usually continues for three years. In the case of seasonal allergies, the dosage can be reduced during the allergy season or the treatment can be suspended entirely.

Short-term hyposensitisation

This type of treatment can be administered to patients with pollen allergies shortly before the respective pollen season begins. This means that "late deciders" for whom conventional allergen-specific immunotherapy is no longer an option can also be treated. The treatment consists of just a few injections with increasing doses of allergen. However, it must be repeated in three consecutive years. It can also be continued after the respective pollen season to make it still more effective.

Rush and ultra-rush hyposensitisation

The dose administered is increased rapidly to achieve high levels of tolerance in a short time (several injections a day, possibly as a hospital inpatient). The treatment then continues with monthly injections for at least three years. This process is commonly used in the case of insect venom allergies, where high levels of tolerance have to be achieved quickly.

Sublingual hyposensitisation

Rather than receiving injections, the patient takes pills or drops; this form of treatment is suitable for people who are allergic to substances such as grass pollen. Drops are held under the tongue for two to three minutes and then swallowed; pills are allowed to dissolve in the mouth. After the first treatment at the doctor's, the patient takes the preparation at home.

Many experts recommend sublingual immunotherapy for people allergic to pollen when injection therapy cannot be used. Before it is administered to children, the efficacy of the preparation must have been proven in studies of corresponding age groups. Because the allergy sufferer's immune system is hypersensitive to substances that are in themselves harmless, this "pathological" mechanism has to be interrupted.

Hyposensitisation can trigger precisely these changes in the immune system. A critical role is played by the T cells, which act as a kind of defence mechanism. T cells trigger allergies by reacting much too violently. Hyposensitisation trains them to be more tolerant. The production of large quantities of additional antibodies during the various phases of treatment can cause the allergic symptoms to decline. The better patients respond to the treatment, the more likely it is that they will require less medication. Hyposensitisation often causes symptoms to disappear completely.

When should hyposensitisation begin?

Experience has shown that children respond better to this treatment than adults. Ideally, it should therefore begin at a young age. The body's tolerance of the allergen is restored in around 85 per cent of cases. An upper age limit - restricting the treatment to patients under 50 - is no longer recommended.

What are the side-effects of hyposensitisation?

Mild local skin reactions - similar to those caused by insect bites - can occur at the injection site. They only give cause for concern if they are unusually large (more than five to ten centimetres). Patients may suffer temporary tiredness, anxiety and headaches; less commonly, respiratory problems and hives may occur. If this is the case, the dosage and intervals at which the patient is injected should be reviewed (individually adjusted).

Severe side-effects (allergic/anaphylactic shock) only occur very rarely. The doctor giving the injections must therefore be able to initiate emergency treatment. The patient must stay at the doctor's surgery for at least 30 minutes following the injection since severe side-effects can occur in this time. Patients being treated with drops or pills may initially experience local symptoms in the mouth and throat (itching).

When does hyposensitisation help?

Hyposensitisation (injections) is highly effective when treating insect venom (bees, wasps), pollen and dust mite allergies; however, only a few studies testify to the efficacy of hyposensitisation when treating animal (cat hair) and mould (alternaria, cladosporium) allergies. The most important strategy in the case of animal allergies is to avoid the animals entirely. Hyposensitisation may help in individual cases where this is not possible. There are currently only a few allergy consultants who carry out hyposensitisation treatment using animal allergens.

Does it also work for asthma?

Hyposensitisation is only recommended in cases of mild, well-controlled allergic asthma to alleviate the symptoms. The therapy is no substitute for proper anti-asthmatic treatment. The doctor must be informed if the patient develops allergic symptoms or other illnesses, is vaccinated or changes the medication.

Sport, other forms of physical exertion and excessive heat (sauna or hot baths) should be avoided on the day of the injection. Asthmatics should check and make a note of their peak flow readings on a regular basis. Patients can take anti-allergic medication during the hyposensitisation treatment since the preparations used (e.g. antihistamines and glucocorticoids) have no impact on the success of the treatment.

TK-Broschüre Allergien

Hahn, J. M.: Checkliste Innere Medizin (E-Book PDF). 7. Aufl. Stuttgart: Thieme, 2013.

Arnold, W.; Ganzer, U.: Checkliste Hals-Nasen-Ohren-Heilkunde. 5., komplett überarbeitete und aktualisierte Aufl. Stuttgart: Thieme, 2011.

Pschyrembel: Klinisches Wörterbuch. 264. Auflage. Berlin: De Gruyter, 2012.

Sterry, W; Burgdorf, W; Paus, R.: Checkliste Dermatologie (E-Book PDF). Venerologie, Allergologie, Phlebologie, Andrologie. 6., vollständig neu bearbeitete Aufl. Stuttgart: Thieme, 2010.

Deutsche Haut- und Allergiehilfe e.V.: www.dha-allergien-vorbeugen.de (Stand 18.12.2014).

Trautmann, A.; Kleine-Tebbe, J.: Allergologie in Klinik und Praxis: Allergene - Diagnostik - Therapie. Stuttgart: Thieme, 2013.

Bundesverband der Pneumologen und Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin e.V. (Hrsg.): www.lungenaerzte-im-netz.de (Stand 18.12.2014).

Deutscher Allergie- und Asthmabund e.V. (DAAB): www.daab.de (Stand 18.12.2014).

Deutsche Gesellschaft für Allergologie und klinische Immunologie (DGAKI) und Deutsche Gesellschaft für Kinder- und Jugendmedizin (DGKJ) in Zusammenarbeit mit dem Ärzteverband Deutscher Allergologen (ÄDA), der Deutschen Dermatologischen Gesellschaft (DDG) et al.: S3-Leitlinie Allergieprävention. AWMF-Leitlinien-Register Nr. 061/016 (Stand: Juli 2014). URL: http://www.awmf.org/uploads/tx_szleitlinien/061-016l_S3_Allergieprävention_2014-07.pdf(Stand 18.12.2014).

Deutsche Gesellschaft Allergologie und klinische Immunologie (DGAKI): Leitlinie: Die spezifische Immuntherapie (Hyposensibilisierung) bei IgE-vermittelten allergischen Erkrankungen. AWMF-Leitlinien-Register Nr. 061/004. Entwicklungsstufe 2 (Stand: 1.9.2009). URL: http://www.awmf.org/uploads/tx_szleitlinien/061-004_S2_Die_spezifische_Immuntherapie__Hyposensibilisierung__mit_Allergenen_09-2009_09-2014_01_abgelaufen.pdf (Stand 18.12.2014).

Online-Informationen der Europäischen Stiftung für Allergieforschung (ECARF): www.ecarf.org (Stand 18.12.2014).