Allergy – an abnormal reaction of the body; caused by certain allergens

An allergy is an abnormal reaction of the body in contact with certain allergens. This phenomenon is caused by some allergen (contact allergens, respiratory or inhaled allergens, ingested allergens …).


The allergy refers to an excessive and inappropriate reaction of the body against a foreign substance, the allergen. This increased sensitivity is to point the origin of disorder, acute or chronic.

Allergies can be respiratory (asthma, rhinitis …), food or skin (eczema, pruritus …) and are increasingly common. Read also: How I suffer allergy?
Usually, the immune systems fight against the harmful elements (bacteria, viruses or parasites).


Sometimes, during a contact with a substance a priori harmless the body reacts abnormally by either reaction hypersensitivity following:
– type 1 (immediate): production of antibodies called immunoglobulin type E (IgE) as in asthma, allergic rhinitis and conjunctivitis, allergic to latex and certain foods
– Type 2 response of cells (macrophages, cytotoxic T lymphocytes …) and complement factors (substances involved in defending the body against infection) as in the acute rejection of the graft after transplantation, hemolytic anemia and some other diseases
– type 3: Action of circulating immune complexes (antigen and antibody associations) as in lupus, bronchopulmonaryaspergillosis;
– type 4 (delayed): participation of different types of T cells (inflammatory cells) responsible among other things, contact dermatitis and several forms of drug hypersensitivity.

Hypersensitivity type 1, the most frequently encountered, is responsible for all diseases caused by an intense production of IgE and many allergic reactions.


Among atopic diseases are:
– the eczema  ;
– contact dermatitis;
– the hives  ;
– angioedema;
– allergy to latex
– allergic disorders of the lungs
– intolerances bites venomous.

In this type of reaction, the immune system is first sensitized during the presentation of the allergen (first contact between the allergen and the immune system): no allergic reaction is visible. It was during the second contact that triggers the disease.


Allergy is caused by certain allergens (contact allergens, respiratory or inhaled allergens, ingested allergens …).

Among the allergens most frequently, you can meet:
– mites;
– cat hair;
– tree and grass pollens  ,
– mold;
– latex
– perfume and cosmetic substances
– Hymenoptera venom (bees, wasps, etc.)
– milk, peanut, egg, fish, kiwi …

The origins of allergy due to IgE are usually linked genes and the environment. The phenomenon is often found in several members of one family. There is a hereditary land-called ” atopic ” in this type of disposition.


Symptoms can vary widely depending on the type of allergy:
– hives
– sneezing;
– cough
– conjunctivitis
– eczema
– asthma or difficulty breathing
– swelling of the lips, eyes, face, tongue, throat
– edema …

The allergic reaction is variable according to the responsible allergen, and the sensitivity of the affected person.

In some exceptional cases, there may be an anaphylactic shock (allergic reaction acute IgE mediated which can be fatal). This is a medical emergency. An immediate injection of epinephrine is needed.


In case of familial predisposition, we must be attentive to young children and set up a number of precautions to limit contact with allergenic substances  :
– Avoid furry animals at home;
– air daily enclosed spaces, including home,
– not too warm;
– do not smoke;
– avoid carpets and curtains;
– long breastfeed her child can protect allergic reactions.

Once the substances causing allergic reactions are known their eviction is highly recommended.

It is advisable to see your doctor for an update from the suspected allergy.


For appropriate care, it is important to know the molecule at the origin of allergic reactions.The circumstances of onset are essential for this suspect or allergens.

Certain laboratory tests (IgE, eosinophil …) can evoke but not confirm an allergic origin.

If the history of the disease and clinical examination fail to find the cause, the allergist can test allergens on the skin. These skin tests determine the substance(s) responsible for allergic reactions.

Two techniques are used: percutaneous (skin-prick tests) and intradermal.

Other tests are possible (RAST (search for specific IgE in serum), provocation tests).


The treatment of allergies is simple, but difficult to follow in everyday life: it is based on the removal of offending allergens.

To treat the symptoms and reduce the severity of the allergic reaction, the doctor may prescribeantihistamines, mast cell stabilizers, and corticosteroids.

In the case of pollen allergy, antihistamines are generally prescribed before the onset of symptoms, so upstream of the pollination period and continued throughout its duration.


The desensitization concerns especially allergies to dust mites, pollens, house dust, fungi, venom of stinging insects and sometimes to penicillin. It does not yet apply to food allergies.

These immune rééqulibrer by exposure to the allergen dose gradually increased (by injection or tablet) to obtain a tolerance of the individual.

Treatment is often long (several years) with no guarantee of success. It can have adverse effects but rarely severe (rash, itching).


In addition to or in anticipation of a medical consultation, homeopathic treatment can be useful against some allergy symptoms.

A homeopathic doctor may prescribe a suitable treatment background and soothe acute manifestations.

For example, Histaminum 15 CH, 1 dose per week extra prevention.


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