An allergy is an immediate hypersensitivity to a substance that produces characteristic symptoms if inhaled, ingested or touched.

The substance to which a person is allergic is called an “allergen”, and the symptoms caused are defined as “allergic reactions”.

Triggering factors

According to the World Health Organisation (WHO), allergies are a common condition affecting more than 30% of the world’s population. Although people may have a genetic predisposition to allergies, environmental factors are also known to trigger allergic reactions.

In recent decades, environmental, habitat and lifestyle changes and an increase in people keeping pets have contributed to the rise in allergies.

A person can become allergic from first contact with an allergen. This is when the sensitisation process begins.

How do allergies occur? Sensitisation process

There are four main components involved in triggering an allergic reaction:

  • Allergen: the substance that causes the allergy.
  • Immunoglobulin E (IgE): an antibody produced by the immune system in response to the allergen that triggers the release of histamine.
  • Mast cells: special cells found in the skin and moist tissues of the body (nose, eyes, mouth), loaded with histamine granules.
  • Histamine: a substance released during the allergy process, which is responsible for allergy symptoms.

During the sensitisation process, the body forms specific antibodies to any foreign substance that enters it. There are several types of antibodies or immunoglobulins: IgA, IgG, IgM, IgD and IgE. The most common allergy is due the body forming IgE against a particular allergen, while non-allergic people use other defence mechanisms.

On the first occasion this IgE level is low, or the amount of allergen is small, and the person appears to tolerate the allergen well. However, prolonged contact with the allergen can cause the IgE level to increase to such a point that it triggers the release of various mast cell and eosinophil components, which lead to allergy symptoms.

The fact that there has to be more than one contact with the allergen or prolonged exposure over time can give a false sense of not having an allergy, because symptoms are only triggered when the allergen level is higher.


Immunotherapy is the mainstay of causal treatments for allergies, as it can act directly on the immune system and thus provide a long-term treatment.

It involves administering gradually increasing amounts of allergens to patients with the aim of improving the symptoms caused by subsequent exposure to the causative allergens. This causes the symptoms to reduce or disappear, leading to less need for medication and an improved quality of life.

In order to make patients as symptom-free as medically possible, immunotherapy treatments can be used in combination with environmental control measures, pharmacological treatments and by educating allergic patients and their families.

This type of therapy is used to treat allergy cases caused by pollen, dust mites, animal dander and certain moulds.

The choice of the most suitable allergen extract for each patient is based on the diagnosis of their allergist. Immunotherapy is administered subcutaneously or sublingually.

In either case, immunotherapy is usually effective. Improvements can be seen within a few months of starting the vaccination, and become apparent around the first year of treatment.


When should immunotherapy treatment begin?

Allergy treatments must be prescribed by a specialist

Healthcare professionals must have the necessary training to apply the treatment, as well as the ability to intervene in any subsequent situations, such as an adverse reaction.

  • Always administer the dose prescribed by your allergist. Should you have any queries or notice any symptoms, please discuss them with your allergist.
  • Apply under the tongue and hold for 3-4 minutes. Swallow the remaining amount. If you notice any pharyngeal discomfort, we recommend spitting out the dose after this time has passed.
  • Take the vaccine on an empty stomach, first thing in the morning. Do not eat for at least 20-25 minutes afterwards.
  • Always take the vaccine at the same time. We recommend setting an alarm on your mobile or watch to avoid forgetting.
  • Store the vaccine in the fridge at a temperature between 2ºC and 8ºC, never in the freezer. Avoid leaving the vaccine in hot places or in direct sunlight.
  • Do not administer the vaccine if:
    • You have poorly controlled asthma or severe allergic symptoms.
    • You have an oropharyngeal, respiratory or oral infection (thrush, gingivitis, etc.).
    • Oral surgery. In this case, apply the vaccine 7 days afterwards.
    • Tooth extraction or tooth loss In this case, apply the vaccine once the wound has healed.
  • We do not recommend administering the allergy vaccine on the same day as other types of vaccines. We recommend allowing at least 3 to 4 days between each one.


  • Keep the windows of your home, especially your bedroom, closed for most of the day. Air your home daily for 15-20 minutes in the late afternoon. Keep your windows closed at night.
  • Limit your outdoor activities at 05:00-10:00 and at 19:00-22:00.
  • Avoid outdoor activities (sports, walking, cycling, etc.) on hot, dry days, as the pollen count is higher.
  • Avoid areas with a higher concentration of plants and trees (parks, gardens, rose gardens, etc.).
  • Wear sunglasses outside, especially on windy days, to protect your eyes from direct contact with the air and the pollen it carries.
  • When you return home, we recommend showering as soon as possible to remove any pollen grains that may have stuck to your clothes or hair.
  • Do not leave clothing worn during the day in your bedroom. Air them outside and, if possible, wash them before wearing them again.
  • Do not dry clothes outside on days with a high pollen count.
  • Keep windows closed when travelling by car and ensure that filters are properly maintained. If travelling by motorbike, we recommend wearing full-face helmets, and always keeping the visor completely closed.