Second opinion on allergen immunotherapy (AIT)

Allergen-specific immunotherapy (AIT) is the only method of allergy treatment that acts on the cause of the disease rather than its consequences. Medical professionals use other terms that slightly vary in different languages: desensitization, allergy immunotherapy. The word "specific" in this case means that the therapy is directed against a certain allergen which triggers patient's body reaction. The term "allergy shots" is also commonly used, although in addition to subcutaneous injections typical of vaccination, sublingual administration is also possible as drops or pills.

How does it work?

The method is based on introducing gradually increasing doses of allergen (e.g., birch pollen) according to a certain scheme. Thus, the immune system gets used to an essentially harmless substance that caused an individual reaction, and stops perceiving it as a danger. However, patience is needed, because one procedure is not enough; the treatment course takes an average of three to five years. The regimen and duration is determined by the attending allergist.

Is desensitization actually vaccination?

There are indeed similarities with preventive inoculation since in both cases the immune system is affected. Yet there is a fundamental difference.

What allergies can AIT treat?

Immunization is especially widely used against the so-called hay fever (allergic rhinitis caused by plant pollen). But in addition to it, therapy can be effective for allergies to:

• insect venom;
• house dust mites;
• mold;
• animal hair.

How do you get your prescription?

First, the doctor carefully collects information about the symptoms, when and where they occur. Next, skin tests and blood tests (e.g. prick test, IgE-specific antibody tests) are performed to determine the allergy trigger, and a provocation test with the suspected trigger (e.g. on the nasal mucosa) is performed to confirm the diagnosis. If there are still uncertainties, doctors can resort to so-called molecular allergy diagnostics. This makes it possible to determine which components of the allergens are the primary ones. This is important for evaluating the potential effectiveness of AIT, since it can only help if the person also reacts to the primary allergens contained in the respective drug substances. In any case, they are not immediately effective, so conventional anti-allergy medication is necessary in the first stages.

AIT medications

To ensure the effect of allergy desensitization, an appropriate drug and a sufficiently long duration of therapy (usually at least three years) are required. Common triggers for which therapeutic allergens are available as ready-to-use preparations include, for example, pollen from early flowering plants and grasses, house dust mites or insect venoms. For rarer triggers, an individualized prescription is made whenever possible.

Injection substances are usually available in the prolonged-release form, as in this case the risk of side effects is much lower. In addition, the treatment does not need to be repeated as often, as the trigger enters the body slowly and consistently due to the depot effect.

What are the forms and regimens of allergy immunotherapy?

For seasonal allergies (early flowering plants, grasses/rye, wormwood), treatment is usually started before the flowering period begins, i.e., in the fall or winter, but can also be carried out in the long term, for three to five years uninterrupted.

If the disease is not time-dependent, AIT can be done in any season and without restriction throughout the year.

There are two main ways of administering the medication – subcutaneous (shots) and sublingual.

Subcutaneous immunotherapy

This is the most common method and its effectiveness has been proven by numerous studies. The allergen solution is injected under the skin on the outer side of the upper arm.

Initial immunotherapy is given as follows:

• Weekly injections for 2-6 weeks.
• Low doses are used at first.
• The dosage is increased gradually until a maximum is reached.

Further maintenance course includes:

• 1 injection every 4-6 weeks for about 3 years.
• The dose of the drug remains the maximum dose.

The procedure is to be performed in a medical facility. After it, it is necessary to stay in the doctor's office for about 30 minutes to make sure that the drug is well tolerated.

Drops or tablets (sublingual immunotherapy)

In this case, the allergen in the form of drops or tablets is placed under the tongue daily, and should ideally stay there for two to three minutes before swallowing. This can be an effective alternative, for example, for children who are afraid of injections or for patients who are short on time. Desensitization using drops can be performed at home.

Initially, the drug is taken daily (it’s advisable to have a medical professional at your side during the first administration), starting with a small dose and increasing it every day until the maximum is reached.

After that the allergen is taken daily for about 3 years at the maximum dose.

Benefits of allergen-specific immunotherapy

Symptoms of allergies, such as plant pollen, occur for many weeks or even months of the year. This affects the quality of life. In particular, it becomes difficult to spend time outdoors or to exercise. It has also been proven that allergic reactions have a negative impact on school performance and adult work performance.

Upper respiratory tract allergies tend to spread more deeply. This means that the inflammation moves down to the bronchi and lungs. Thus, a seemingly "banal" hay fever can develop into allergic asthma. That is, the disease affects the next, deeper, level. This can happen in so-called respiratory allergies (to pollen, animal hair, etc.) and is observed in about 40% of all respiratory allergic patients who did not treat the cause of their disease in time. Allergy immunotherapy literally "gets to the root" of the allergy. Specific immunotherapy is particularly successful in reducing the risk of asthma in children. In addition, the likelihood of disease recurrence (resensitization) can be reduced.

Are there any side effects?

As with all therapies, side effects are generally possible.

A distinction must be made between local and systemic manifestations. The former only occur at the injection site, while systemic effects appear in other areas or throughout the body.

If drops or tablets are used, itching, tingling and slight swelling of the oral mucosa sometimes occur at the beginning of treatment, but these usually subside after a few weeks.

When immunotherapy is performed by injection, an adverse reaction usually occurs within the first 30 minutes after the shot. Therefore, it is very important that the patient remain in the doctor's office during this time. The following undesirable but mostly harmless side effects are relatively common:

• mild skin reaction at the injection site (redness or swelling);
• swelling of the arm.

Rare complications include:

• itching;
• skin rash;
• cough;
• shortness of breath;
• palpitations;
• dizziness.

If there are signs of shock, the doctor should be notified immediately. The allergist's office always has appropriate medications available to treat possible side effects.

Systemic reactions are rare (about 1%) and may manifest as asthma, gastrointestinal complaints, nausea, etc.

What are the chances of allergen immunotherapy success?

Statistically, the probability that one can get maximum effect depends on the type of allergy:

• to pollen: 80 to 90%.
• to mites: 70 to 80%.
• to insect venom: 95%.