Desensitization (allergen specific immunotherapy)


What is it about ?

Many people suffer from one form or another of allergy from an early age. Substances that you may be allergic to are called allergens. For example, grass pollen, animal hair, house dust, certain foods, etc. When an allergic person comes in contact with these substances, the body reacts by producing an abnormal amount of antibodies. Sometimes the person feels absolutely nothing and other times the allergy can trigger a multitude of symptoms: sneezing, runny nose, red eyes, asthmatic symptoms or even a shock reaction which can be fatal.

Symptomatic treatment at the time of complaints is not always enough, because it often comes too late and does not cure the condition. This is why we have developed treatments that offer a long-term solution. Immunotherapy for example, which is also called desensitization or hyposensitization treatment: the body is gradually accustomed to an increasing amount of the allergen (desensitization) in order to reduce the strong reaction occurring in the event of an allergy.

This treatment can be applied from the age of 5 years. Since immunotherapy attacks the root cause of the problem, the result is durable in the long term in 8 to 9 out of 10 people. In children allergic to grass pollen, a lasting effect has been shown to extend over a period of time. dozen years. If you are allergic to bee and wasp venom, immunotherapy suppresses the potentially fatal reaction in 8 out of 10 people.

Who is it suitable for?

Immunotherapy is started only in the following situations:

  • This is a proven allergy, preferably for a limited number of allergens. It is not possible to develop a treatment for say 20 different allergens.
  • There can be no contraindication to treatment. Contraindications are, for example,
    • Medicines that suppress immunity,
    • Cancer,
    • The pregnancy,
    • Breastfeeding
    • An age of less than 5 years.
  • The person must be prepared to undergo the treatment because it takes time and it is not cheap. The treatment should be continued for 3 years and even 5 years in case of allergy to bees and wasps.
  • Treatment should be started at an early stage of the allergy.
  • Only trained persons, who can assess the effect and react appropriately in the event of complications, can administer the treatment.

How does your doctor decide if this treatment is right for you?

The results are better for some allergens than for others. The nature of the symptoms is also important: this treatment is only given if the allergic symptoms have a significant impact on the quality of life. Usually, immunotherapy alone is not enough. People with asthma in particular always need their medication (an inhaler, for example).
In general, immunotherapy gives a favorable result in the following cases:

  • allergy to insect venom (wasps, bees);
  • sneezing, runny nose and conjunctivitis due to an allergy to pollen, dust mites and animals;
  • allergy to dust mites and (domestic) animals;
  • asthma caused by an allergy to pollen, dust mites and animals;
  • allergy to fungi;
  • occupational allergies.

What can your doctor do?

The doctor will be able to make the correct diagnosis on the basis of a blood test and after having performed skin tests. If possible on the basis of the results, he will prepare a solution of the allergen or a mixture of several allergens. This preparation is then injected under the skin, in increasing concentration.

We always start with a strongly diluted solution, so as not to provoke too strong reactions. The injections are given twice a week. The concentration is increased every two weeks, up to the maximum tolerated dose. Then, the interval between 2 injections is gradually extended to 1 injection every 4 to 6 weeks. The dose is reduced a notch in the event of a severe reaction, such as a red patch at the injection site that is larger than the palm of your hand, a generalized rash, or asthma attack. During pollen season, the dose may also depend on symptoms.

If you are allergic to grass pollen or birch, immunotherapy can be given under the tongue. The first administration should be carried out by the doctor. Almost everyone who takes this treatment experiences a temporary tingling sensation in the mouth. After a week, you can continue the treatment at home.

What can you do ?

After treatment, wait half an hour to see if there is any adverse reaction. Do not exercise vigorously and do not drink alcohol. You will be given medicine for reactions that may occur later in your home. Write down any reactions in a journal.

In consultation with the doctor, you should assess the effect of the treatment on the symptoms. The treatment will be evaluated at least once a year.

Want to know more?

Source

Foreign clinical practice guide ‘Allergen immunotherapy (desensitization)’ (2000), updated on 31.05.2017 and adapted to the Belgian context on 05.02.2020 – ebpracticenet