Desensitisation: how to get rid of allergies

Desensitisation is also known as hyposensitisation, allergy vaccination or specific immunotherapy (SIT). This therapy involves targeted training to help the immune system get used to the allergen, i.e. to the substance that triggers the allergic reaction. 

If we have an allergy, our immune system is overly sensitive in the way it reacts to a substance that is actually harmless. This leads to symptoms such as watery eyes, shortness of breath and even circulatory arrest. Desensitisation is a way of trying to train the immune system out of this over-reaction by gradually allowing it to get used to the allergen.

The first step involves a physician carrying out an allergy test to identify the allergen. The immune system is then repeatedly and deliberately confronted with this allergen. The dosage starts off small and then continues to increase. This is known as the increased exposure phase. When the individual’s maximum tolerance dose is reached, this amount will continue to be administered on a monthly basis. This is the maintenance phase. The body’s allergic reaction can lead to side effects during both phases. Find out more in the text below.

Desensitisation is successful if the allergy symptoms are reduced on a long-term basis or, ideally, if they stop occurring altogether. The chances of this happening are high; the therapy is successful in around 80% of cases. However, success cannot be guaranteed.

What types of desensitisation are there?

There are two types of desensitisation. Subcutaneous Immunotherapy (SCIT) involves injecting the allergen underneath the skin, for example into the upper arm. With sublingual Immunotherapy (SLIT), the substance is administered under the tongue, either as a liquid solution or in the form of a tablet. 

Desensitisation must be prescribed by an allergist. The treatment, however, can be carried out by a general practitioner or paediatrician with experience in this field. 

Desensitisation can be used to treat over-reactions to the following allergens:

• Pollen
• Dust mites
• Mould
• Animals, e.g. cat hair
• Bee and wasp venom

These are known as immediate allergies. As the name suggests, these allergies cause the immune system to react to the allergen very quickly, i.e. within seconds or minutes.

Contact allergies, such as those to nickel or arnica, cannot be treated using desensitisation. This is because contact allergies have different immunological causes to immediate allergies.

An allergist will decide whether desensitisation is a potential therapy option. Frequent exclusion criteria include pregnancy at the start of treatment, cardiovascular diseases, taking beta-blockers and severe autoimmune diseases or uncontrolled asthma. 

Desensitisation usually takes three years, except in the case of allergies to insect venom. For allergies to wasp or bee venom, treatment tends to take three to five years. 

There are a number of side effects that can occur during desensitisation.

Minor side effects include fatigue and allergic reactions such as sneezing or watery eyes. The injection site can also become red, swell up or start to itch.

More serious side effects include hives over the entire body – i.e. raised itchy and red dots on the skin – or swelling in the throat area. Both are easy to treat.

The most serious possible side effect, anaphylactic shock, rarely occurs. This type of allergic reaction can lead to respiratory and circulatory arrest. This is why emergency medication is always on hand in the practice.