An allergy is an overreaction of the immune system to particular substances foreign to the body. These substances, also known as allergens, enter the body through the skin, the digestive tract or the respiratory tract. They start an allergic reaction that can cause nasty symptoms. Allergy is the most common chronic disease.
In the event of an allergic reaction, an allergen activates the immune system. This system recognizes the allergen as ‘enemy’, wants to disarm it and produces particular proteins, called antibodies. As a consequence, a series of reactions is initiated, in which strong chemical substances, such as histamine, are released. Not the allergens themselves, but these chemicals cause allergic symptoms. An allergic reaction can occur immediately (within a few minutes to several hours) or delayed (after a few days). Why a person gets an allergic reaction is often not clear. Allergies are not contagious, but there may be a genetic predisposition. The more family members have allergies, the greater the chance that a child develops an allergy too.
Different allergens provoke different symptoms. There are three types of symptoms:
- Respiratory problems. Problems arise, such as a runny nose, itchy red eyes, sneezing and difficulty swallowing. The most common respiratory allergy is the allergy to pollen, also known as hay fever.
- Problems of the digestive tract. Eating certain foods can cause gastrointestinal symptoms, such as itching and swelling of the tongue and the larynx, vomiting, abdominal cramps and diarrhea.
- Skin problems. The cause is often an allergen that is eaten or inhaled. Direct skin contact with certain substances can also cause an allergic reaction. Symptoms occur in the form of rash (eczema), pain, redness, swelling and itching of the skin.
A very severe allergic reaction is called anaphylaxis or anaphylactic shock. This can occur, for example, after a wasp sting. As a result, the tongue, lips and eyelids can swell with (serious) chest tightness, because moisture can get into the lungs. This complication can be fatal and requires immediate medical intervention.
Based on the symptoms, the course of the symptoms and physical examination, the diagnosis of allergy is sometimes immediately clear. In addition, more investigation can be done in the form of an allergy test to see exactly which allergens cause the allergic reaction:
- In a skin test, allergens are applied on or in the skin. On the basis of the resulting response can be determined for which substance a person is allergic.
- During a provocation test, the respiratory response is measured after inhaling a triggering substance. This can be an allergen or a general triggering substance, such as histamine.
Allergy can also be determined by testing for a type of protein in the blood, called IgE.
When an allergy is identified, it can be treated in several ways:
- Avoiding the allergen. Care should be taken to ensure that the patient doesn’t come into contact with the substance causing the allergic symptoms (also called decontamination). In practice, however, complete avoidance of allergens is almost impossible. Pollen, by example, are floating through the air and one really ever encounters the cat from someone else.
- Medicines. The group of medicines used to treat allergic symptoms is known under the collective name symptomatic medication (or simply suppressants). These medicines block the effect of histamine, thus reducing the symptoms. Examples of this type of medicines are: antihistamines, corticosteroids and nasal decongestants.
- Immunotherapy. The use of immunotherapy aims to address the underlying cause of the allergy. For an extended period of time, a certain amount of the allergen is administered. This allows the immune system to become accustomed to this substance. The immune system can eventually respond less or no longer to the allergen, which results in having less or no allergy symptoms. The total treatment takes three to five years.
The prospects are associated with the type of allergic reaction, the type of allergen, the severity of the condition and the age at which the allergy has begun. Allergic reactions that often occur in young children, such as milk proteins allergy, may decrease as the child grows older. Part of the patients, however, suffer a lifelong allergic condition. Allergic reactions that occur later in life, usually remain.
- Use the medication timely to prevent allergic reactions.
- Breastfeeding, preferably during six months, may help preventing allergies in the child.
- Avoid known food allergens during the first year, such as peanuts, egg, soy, milk, wheat and nuts.
- Keep the house clean. Care should be taken that all corners in the bedroom and the living room are well cleaned. Wipe off smooth furniture and hard floors with a damp cloth. Vacuum the bedroom and living room regularly (two to three times a week), using a HEPA filter.
- Try to keep the air in the house as dry as possible. Allergens, such as dust mites, love humidity. Good ventilation in the house reduces dust mites. Use a proper ionizer (air purifier).
- Use anti-dust and anti-allergen bedding. There are special covers for sale for duvet, mattress and pillows. With these so-called allergy covers, people can protect themselves from dust mites.
- Make sure that there is no smoking done inside the house.
- The term ‘allergy’ is derived from the Greek word állos (different, strange).
- The prevalence of allergy is 25% and continues to increase, particularly in children.