The document discusses allergies, which occur when the immune system reacts to normally harmless substances called allergens. Common allergens include pollen, animal dander, foods, insect bites, medicines, and plants. Allergic reactions can affect the skin, respiratory tract, sinuses, and digestive system, causing symptoms ranging from mild to severe like hives, swelling, coughing, wheezing, and anaphylaxis. Allergies are caused by both genetic and environmental factors. Avoiding allergens is the best prevention strategy when possible.

1. The allergies

2. The allergy
Allergy occurs when a person's immune system reacts to substances in the
environment that are harmless for most people. These substances are known
as allergens and are found in dust mites, pets, pollen, insects, ticks, moulds,
foods and some medicines. Atopy is the genetic (inherited) tendency to
develop allergic diseases. People with atopy are said to be atopic. When atopic
people are exposed to allergens they can develop an immune reaction that
leads to allergic Inflammation.
Common allergens include pollen and certain food. Metals and other
substances may also cause problems. Food, insect stings, and medications are
common causes of severe reaction. Their development is due to both genetic
and environmental factors.

3. Causes
Among the most common allergens are:
 Animal dandruff
 Stings of bees or other insects
 Food, especially nuts, fish and seafood
 Insect bites
 Medicines
 Plants
 Pollen

4. Types of allergy
Skin: Substances that come into contact with the skin, such as latex, are also common
causes of allergic reactions, known as contact dermatitis or eczema. Skin allergies
frequently cause rashes, or swelling and inflammation within the skin, in what is known as
a "wheal and flare" reaction characteristic of hives and angioedema.

5. Food allergy
A wide variety of foods can cause allergic reactions, but 90% of allergic responses to
foods are caused by cow's milk, soy, eggs, wheat, peanuts, tree nuts, fish, and
shellfish. Other food allergies, affecting less than 1 person per 10,000 population,
may be considered "rare". The use of hydrolysed milk baby formula versus standard
milk baby formula does not appear to change the risk.

6. Latex can trigger an IgE-mediated cutaneous, respiratory, and systemic reaction.
The prevalence of latex allergy in the general population is believed to be less
than one percent. In a hospital study, 1 in 800 surgical patients (0.125 percent)
reported latex sensitivity, although the sensitivity among healthcare workers is
higher, between seven and ten percent. Researchers attribute this higher level tox
the exposure of healthcare workers to areas with significant airborne latex
allergens, such as operating rooms, intensive-care units, and dental suites. The
most prevalent response to latex is an allergic contact dermatitis, a delayed
hypersensitive reaction appearing as dry, crusted lesions. This reaction usually
lasts 48–96 hours.
Latex

7. Pharmacological allergies
Pharmacological allergy involves an immune response in the body that produces an
allergic reaction to the medicine. It is possible that the first time you take the
medication you will not have problems. But the immune system can produce a
substance (antibody) against that drug. The next time you take the drug, the antibody
tells white blood cells to produce a chemical called histamine. Histamine and other
chemicals cause the symptoms of your allergy.

8. Rhinitis
It is called allergic rhinitis when the typical symptoms (nasal congestion,
rhinorrhea, sneezing or nasal itching) are the result of a hypersensitivity reaction
in the majority, IgE type, so it can also be called allergic rhinitis mediated by IgE.
once, depending on the duration of the symptoms, it is subdivided into
intermittent and persistent; seasonal allergic rhinitis refers to seasonal episodes,
such as allergic rhinitis induced by pollen. In relation to the effect of symptoms
on daily activities and sleep, it can be referred to as mild or moderate severe.

9. Allergy to insect bites
Hypersensitivity to poison or insect saliva mediated by an immune mechanism is
called a venom or saliva allergy, as in the case of allergy to bee venom. It can be
called allergy to IgE-mediated poison if you want to highlight the role of IgE. The
large amount of venom allergen in a single bite can be compared with years of
inhaling pollen allergens.Other reactions are grouped under the term
hypersensitivity to non-allergic insect venom.

10. Asthma
It is called allergic asthma when it is caused by immunological reactions, which
in most cases are initiated by antibodies of the IgE type, so it can also be called
allergic asthma mediated by IgE.
Conjunctivitis
The frequent association of allergic conjunctivitis mediated by IgE
with allergic rhinitis makes the term allergic rhinoconjunctivitis
the most appropriate for its denomination. In addition to IgE-
mediated conjunctivitis, allergic contact conjunctivitis may appear,
which involves Th1 lymphocyte activation mechanisms.

11. Allergy to animals
First of all we will highlight the cat, which gives frequent allergic problems and which
can be severe. The dog also causes allergies, although comparatively with cats and
horses are not as frequent, despite being the most common animal in the houses. The
horse gives severe problems, although they are not so frequent. Any other hair animal
can cause allergy: hamster, rabbit, ferret, cow, sheep, pig, goat, chinchilla, mouse, rat,
etc.
People become allergic to animals with which they have direct or indirect contact. As
dogs and cats are the most common animals, they are the ones that cause the most
frequent allergy. But people who work with laboratory animals can become allergic to
those animals. People who live on farms can develop an allergy to farm animals. On a
farm, deer allergy has even been proven.

12. Symptoms
Allergy symptoms, which depend on the substance involved, can affect the
respiratory tract, the sinuses and nostrils, the skin and the digestive system. Allergic
reactions can range from mild to severe. In some severe cases, allergies can trigger a
life-threatening reaction, which is known as "anaphylaxis“. The common symptoms
of a mild allergic reaction are:
 Hives (especially in the neck and face)
 Itch
 Nasal congestion
 Rashes
 Red, watery eyes

13. The symptoms of a moderate or
severe allergic reaction are:
 Abdominal pain
 Abnormal breath sounds (garish)
 Anxiety
 Discomfort or tightness in the chest
 Cough
 Diarrhea
 Respiratory difficulty, wheezing
 Difficulty swallowing
 Dizziness or vertigo
 Flushing or redness of the face
 Nausea and vomiting
 Palpitations
 Swelling of the face, eyes or tongue
 Loss of consciousness

14. Prevention
Avoiding an allergen is better than trying to treat an allergic reaction. Avoiding a
substance can mean stopping using a certain drug, installing air conditioning
with filters, giving up having a pet at home or not consuming certain kinds of
food. Sometimes a person allergic to a substance related to a particular job (for
example, flours, woods, etc.) is forced to change jobs. People with strong
seasonal allergies may consider moving to a region where there is no such
allergen.
When contact with the allergen can not be completely avoided, it is
recommended to reduce the exposure to it. For example, a person allergic to
house dust can remove all furniture, carpets and curtains that accumulate
mites; cover mattresses and pillows with plastic protectors; Remove dust and
clean rooms with a damp cloth and quite often; use air conditioning to reduce
the high internal humidity that favors the multiplication of dust mites; and install
highly efficient air filters.