Allergy is a reaction of the organism to particular substances present in the environment, for example in the air or in food.

Allergies are widespread, affect about one in four people, can appear at any time in life (read the Hoax) and can be both temporary and permanent.

Having an allergy can cause discomfort of varying degrees and affect daily activities. Most allergic reactions, however, are mild or moderate and can be controlled.

More rarely, severe allergic reactions may occur such as, for example, anaphylactic shock which constitutes a "medical emergency and requires urgent care."

The substances causing allergic reactions are called allergens. Usually, if you come into contact with them, the allergic reaction appears quickly, within a few minutes.

The most common disorders (symptoms) related to an allergy are:

  • sneezing
  • stuffy or runny nose
  • Red eyes with itching and tearing
  • wheezing and coughing
  • redness and itching on the skin
  • manifestation or worsening of asthma

It would be wise to consult your doctor if an allergic reaction is suspected.

Your family doctor will help manage and treat the condition in milder cases: if the allergy is particularly severe or it is unclear what you are allergic to, you may be referred to an allergy specialist for diagnosis and treatment.

In many cases, the most effective way to manage an allergy is to avoid, when possible, the allergen that causes the reaction; There are also several medications available to control disorders (symptoms) due to allergic reactions (e.g. antihistamines and decongestants).

In case of severe allergies or in case of worsening of the disorders (symptoms), treatment with the responsible allergen, called specific immunotherapy, may be recommended.

We must distinguish between:

  • allergy, specific reaction produced by the immune system when exposed to a normally harmless substance, even in minimal quantities
  • sensitivity, exaggerated increase in the normal effects of a substance: for example, the caffeine in a cup of coffee can cause extreme disturbances (symptoms), such as palpitations and tremor
  • intolerance, when a substance causes unpleasant symptoms, such as diarrhea, but does not involve the immune system; in general, people with an "intolerance to certain foods can eat small quantities without having any problems."


Symptoms of an allergic reaction usually develop within minutes of exposure to the allergy-causing substance.

The most common complaints of an allergic reaction include:

  • sneezing and itchy nose, stuffy or runny nose (allergic rhinitis)
  • Red eyes, tearing and itching (conjunctivitis)
  • wheezing, chest tightness, shortness of breath and cough
  • skin rashes (hives), redness, wheals and itching
  • swelling of the lips, tongue, eyes or face
  • abdominal pain, nausea, vomiting or diarrhea
  • reddened skin, cracked or dry

Disorders (symptoms) vary according to the type of substance you are allergic to and how you come into contact with it.
Consult your doctor if you suspect an allergic reaction.

Severe allergic reaction (anaphylaxis or anaphylactic shock)

In rare cases, allergy can lead to a severe reaction, called anaphylaxis or anaphylactic shock, which can be life-threatening; it usually develops within minutes of exposure to the allergy-causing substance.

In addition to the symptoms above, the signs of anaphylaxis include:

  • swelling of the throat and mouth
  • difficulty breathing
  • dizziness
  • confusion
  • cyanotic skin or lips
  • collapse and loss of consciousness

Anaphylaxis is a medical emergency that requires immediate treatment.



The substances that cause allergic reactions are called allergens. The most common allergens include:

  • pollen of herbaceous plants and trees, allergy to herbaceous plant pollen is often referred to as hay fever (allergic rhinitis)
  • dust mites
  • animal derivatives (hair, dandruff, saliva, urine)
  • foods, especially nuts, some fruits, shellfish, eggs and cow's milk
  • substances transmitted through insect bites and stings
  • drugs, eg ibuprofen, aspirin, some antibiotics, diagnostic contrast media
  • latex, used for disposable gloves, condoms
  • household chemicals, including those in detergents and hair dyes

Most of these allergens are generally harmless to people who are not allergic.

It is not completely clear why the immune system reacts to certain substances in some people by producing the allergic reaction, but it is likely that genetic aspects affect since in most cases there is a family history of allergies or there are related clinical situations. such as asthma or eczema.

The number of allergy sufferers is increasing every year in economically developed countries; the reasons are not fully understood, but one of the main theories is that it can be associated with lifestyle in an environment that is too clean and free of germs. Reducing the number and type of germs our immune system encounters over the course of a lifetime could cause an overreaction when it comes into contact with normally harmless substances.



The family doctor will be able to treat minor allergies due to a clearly identifiable cause, but in more serious cases or where it is difficult to identify the responsible allergen, it is advisable to refer to the allergist specialist for a correct diagnosis.

The tests that can be performed are described below:

Skin prick test

It is one of the most common allergy tests. It consists of putting a drop of the different allergenic extracts on the forearm. The skin under the drop is then gently scratched with a needle. If there is an allergy to the test substance, a wheal (very similar to a sting) will appear on the skin within 15 minutes. The prick test is painless and very safe. You should not take antihistamines before the test as they can interfere with the results.

Blood analysis

Blood tests may be ordered in conjunction with or in place of the prick test to help deepen the diagnosis of an allergy. A small amount (sample) of blood is taken and analyzed for a particular type of specific antibodies produced by the immune system in response to an allergen.

Patch test

The Patch test is used to diagnose a type of eczema known as contact dermatitis, which can be caused by exposure of the skin to allergens generally of a chemical nature. A small amount of the suspected allergen on special metal supports is brought into contact direct with the skin for 48 hours, and then monitor any reactions.

Elimination diet

If a food allergy is suspected, under the supervision of a specialist, the imputed food is eliminated from the diet to see if the symptoms improve. After a few weeks, the specialist will ask to reintroduce the eliminated food to check if it causes a reaction again.

Provocation test

In some cases, the provocation test can be used which consists in the direct administration of the suspected allergen, for the same natural route of exposure (inhalation, oral). Starting from a very low dose, the allergen will be administered in increasing quantities, until a reaction is observed. It is the most accurate test for the correct diagnosis of food allergy. The provocation test must take place under strictly controlled conditions, with health personnel equipped with drugs to deal with any emergencies. It should not be done in patients who have already had anaphylactic shock.

Allergy tests should be conducted and interpreted by a qualified allergy professional who is aware of the symptoms and medical history.



The treatment of an allergy depends on several factors, including the type of ailment (symptoms), the severity, the substance that causes it. In many cases, the family doctor will be able to offer advice and treatment. Different approaches are available. .

Avoid exposure to allergens

It is often the best way to keep symptoms under control, although it may not always be easy to do.
For example, they can be managed in this way:

  • food allergy, carefully considering what you eat
  • allergies to animalskeeping pets out of the house as much as possible and washing them regularly
  • mold allergies, keeping the house dry and well ventilated
  • hay fever, staying indoors and avoiding green areas during the pollen season
  • allergies to dust mites, using hypoallergenic duvets and pillows, eliminating carpets etc.

Medicines to control symptoms

Some mild allergy medications are available at pharmacies without a prescription, but it is always wise to ask your pharmacist or family doctor before taking any new medicine.


Antihistamines are the most commonly used drugs for allergies. They can be taken to treat or to prevent allergic reactions. Antihistamines are marketed for both general and local use, in the form of tablets, capsules, creams, eye drops or nasal sprays.


Nose decongestants can be used as a short-term treatment. They are available in the form of tablets, capsules or nasal sprays. They should not be used continuously for more than a week, as use for long periods can worsen symptoms.


Steroid medications can help reduce inflammation caused by an allergic reaction. They are available for both general and local use such as:

  • nasal sprays and eye drops for rhinitis and conjunctivitis
  • creams for eczema and contact dermatitis
  • inhalers for asthma
  • tablets for hives

Desensitizing therapy (specific immunotherapy)

It is especially indicated in patients suffering from respiratory allergies to pollen, mites or molds and allergy to insect bites (hymenoptera). Desensitizing therapy is based on the principle of administering (either by subcutaneous injection, or in the form of sublingual drops or tablets) to the patient small, progressively increasing quantities of the allergens that cause the allergic reaction. The purpose of the treatment is to modulate the immune system's responses to the responsible allergen in order to reduce or eliminate the most serious reactions. It is recognized by the "World Health Organization (WHO) as the only treatment that can" lead to healing of the "allergy and change the patient's quality of life". The prescription and treatment must be carried out by an allergist specialist after a thorough diagnostic process.
The injection treatment must be carried out under medical supervision, as it is not exempt from the risk of reactions, even serious ones. Treatment with drops or tablets can generally also be done at the patient's home.

Treatment of severe allergic reactions (anaphylactic shock)

Known reactions as anaphylaxis or anaphylactic shock may occur in some people with severe allergies. It arises suddenly and represents a threat to life. It is a condition that requires medical first aid. Whether it is for adults or children, the administration of adrenaline is the basis of the treatment; other therapeutic interventions include the use of antihistamines. There are some devices available for intramuscular self-injection that patients at risk can carry with them and self-administer in case of danger. Immediate administration of adrenaline intramuscularly is often the life-saving intervention, but repeated doses may be necessary in combination with others. Medicines Once discharged, patients should be monitored for up to 48 hours.



The best way to prevent an allergic reaction is to avoid the substance you are allergic to, even if this is not always easy to do.

Here are some tips that should help you avoid the most common allergens.

Dust mites

One of the main causes of allergy are dust mites, small arthropods found in house dust. It is possible to limit the number of mites in the home by avoiding rugs and sofas or upholstered beds, curtains and carpets, using hypoallergenic mattresses, duvets and pillows or anti-mite covers, passing a vacuum cleaner with a HEPA filter (High Efficiency Particulate Air) and regularly cleaning the surfaces with a clean damp cloth.


It is not the pet's fur that directly causes the allergic reaction as much as the fragments of skin and dandruff, and dried saliva and urine, often carried by the hair. If it is not possible to remove the pet, you can try to:

  • keep pets out of the house as much as possible, or limit them to a particular area of ​​the house
  • do not allow the pet to enter the bedrooms
  • washing pets, at least once a week
  • regularly wash bed linen and pillows used by the animal

To visit a friend or relative with a pet, ask not to dust or vacuum the same day to avoid recirculating allergens, and take an antihistamine drug about an hour before entering the house (can help reduce symptoms).

Mold spores

Particles (spores) released by molds can cause allergic reactions. It is possible to prevent:

  • keeping the house free of moisture and well ventilated
  • removing the plants from the apartment
  • eliminating sources and areas of humidity and condensation in the house
  • drying laundry outside the home

Food allergy

By law, food manufacturers must clearly state on the label if they contain substances known to cause allergic reactions. Therefore, the list of ingredients on the label should be carefully checked. People with food allergies should be especially careful when going to restaurants. In this case, it is advisable not to rely only on the menu (many sauces or condiments may contain allergens that are not clearly indicated) but to communicate your dietary needs to the restaurant staff and not to risk in case of doubts. Remember that simple dishes are less likely to contain "hidden" ingredients.

Hay fever

Pollen allergy is commonly known as hay fever or allergic rhinitis. Generally, people are affected between spring (trees) and summer (grasses) but it depends on the type of pollen you are allergic to; for example, some tree families release pollen during the winter. If possible, avoiding exposure to substances that trigger disorders (symptoms) is certainly the safest way to prevent, even if it is not always feasible or simple. For example, avoid cutting the grass, playing or walking in grassy and wooded areas, especially in the early morning, evening and night, when pollen release is at its maximum; take a shower and change your clothes when you return after going out. It may be useful to check the pollen counts in your area, if available.

Insect bites

After having a major reaction to an insect bite, it is advisable to take precautions to minimize the risk:

  • limit exposed skin
  • wear shoes
  • apply insect repellent
  • avoid wearing perfumes, as they can attract insects

Preventing severe allergies (anaphylaxis)

If you are at risk of a severe allergic reaction (anaphylaxis), make sure you always have two adrenaline auto-injectors with you. However, it is a condition that requires emergency treatment and emergency medical attention. It is recommended that teachers, co-workers, and friends be made aware of your allergy so that they can administer the adrenaline injection in an emergency while waiting for an ambulance.



NHS Choices. Allergies (English)

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