Allergy Guide: know the different types and how to treat


What is allergy?

Allergy occurs when the immune system reacts to generally harmless substances. Such elements are known as allergens and can induce a hypersensitivity reaction (allergy), causing inflammation in vulnerable people.

The allergic process usually occurs in atopic patients, that is, people with a genetic tendency to develop diseases of this type. When there is contact with a certain allergen, the immune system responds with antibodies and releases certain substances, such as histamine, responsible for the swelling and irritation present in the allergy.

The substances that most cause allergic reactions are found in dust mites, pollen, pets, insects, food, medicines and mold. It is important to note that each organism reacts differently. Therefore, allergens vary from person to person.

Types and Causes

Basically, allergic reactions can be differentiated by their causes and regions of the body they affect. The most common types are:

Respiratory allergies

This type of allergy affects the respiratory tract, composed of the nasal cavities, pharynx, larynx, trachea and bronchi. The most common manifestation is allergic rhinitis, which registers more than 2 million cases per year in Brazil.

Allergic rhinitis

Known as fever hay, can manifest in two ways: seasonal (occurs only in part of the year) and perennial (occurs all year). Rhinitis can be caused by several factors, such as pollens, hair, mites, mold, cigarettes and even perfume. Symptoms include itching, watery eyes, runny nose and sneezing.

This type of respiratory allergy also has a genetic factor as a cause in most cases.

 that the condition is a contact dermatitis . This condition is caused after contact with certain substances. It can be classified into two types: irritative and allergic. Its most common causes are: detergents, shampoos, metals, varnishes, topical medications, latex gloves.

Atopic dermatitis (eczema)

Chronic condition often associated with food allergy, allergic rhinitis and asthma, atopic dermatitis usually appears in childhood. It causes dry, red and irritated skin, as well as itching. Triggers include some foods, animal dander, dust mites, sweating, wool and soaps.

Read more: Dermatitis: what it is and treatments

Allergy to insect bite (stropula)

After suffering a bite, some people have allergic reactions to insect venom. The biggest cause is bees, wasps and ants. It is important to note that some reactions are common in all people and are not necessarily allergies. In allergic conditions, symptoms such as pain, redness, swelling and itching occur at the site of the bite, which last for a longer time. In more severe cases, an anaphylactic reaction is possible.

Latex allergy

Allergic reactions to latex occur in people who are allergic to the protein present in products made with natural rubber. This component is quite common in medical and dental materials (gloves, bandages, dressings), condoms, balloons, toys, glasses and tires. The condition is more common in the medical profession, due to direct and daily contact with latex.

Cold allergy

Although rare, exposure to cold can cause skin allergies in the form of rashes and itching. The condition manifests itself after exposure to low temperatures, contact with cold water or cold objects and ingestion of cold food or drinks.

Allergy to cosmetics

Some beauty products, such as shampoos, perfumes, soaps and makeup items, can irritate your skin and cause skin rashes, dermatitis and hives. In some cases, there may still be difficulty in breathing and irritation of the mucosa. It is caused by synthetic or natural allergens present in the composition of cosmetics.

Nickel allergy

Widely used in jewelry and accessories, nickel is a metal that has a high allergic potential. Symptoms usually appear 12 to 48 hours after contact and include itching, redness, rashes and swelling. In more serious situations, the skin can become infected, causing burning and pus.

Food allergy

Food allergies occur when there is an abnormal reaction to food proteins, and manifestations can appear even days after ingestion. Symptoms can affect the skin, the gastrointestinal tract, the cardiovascular system and the respiratory tract.

Among the foods that can cause allergy are:

  • Soy;
  • Milk;
  • Peanut;
  • Gluten;
  • Fish;
  • Egg;
  • Nuts;
  • Chestnuts;
  • Fishes and sea food;
  • Wheat.

Food allergies are more common in childhood and tend to be overcome more easily compared to adulthood. The duration of allergies can also vary according to the food: peanuts, chestnuts, fish and typically persistent seafood.

Allergy to cow’s milk (APVL)

More common in children in the food transition phase, cow’s milk allergy is an immune system reaction to proteins in milk.

The condition can cause gastrointestinal symptoms (stomach pain, vomiting, gas , diarrhea ) and in the respiratory tract (wheezing). In addition, it can progress to a more serious reaction, known as Food Protein-Induced Enterocolitis Syndrome (FPIES), which causes intense intestinal inflammation.

Intolerance or allergy?

Despite having similar symptoms, intolerance is different from food allergy. In the first case, the body has difficulty digesting and there is no interference from the immune system. In the allergic process, there is an abnormal reaction triggered by the immune system, which can lead to more serious complications.

It is important to know how to differentiate the condition to prevent allergic reactions in proven cases of food allergy.

Drug allergy

The use of drugs without medical guidance can pose a threat and cause serious reactions in allergic people, such as drop in blood pressure, shortness of breath and even anaphylaxis . If the patient notices any different reactions after using a medication, it is possible that there is an allergy.

The main causes of drug allergy include:

  • Painkillers;
  • Anti-inflammatories (Aspirin, Ibuprofen, Dicoflenaco);
  • Antibiotics (Penicillin);
  • Chemotherapy.

The diagnosis of this condition can be made through the patient’s history. It is important that the doctor and the dentist are aware of possible reactions to prescribe the appropriate treatment in these cases.

Eye allergy (allergic conjunctivitis)

This inflammatory reaction is caused by contact with different types of allergens. Symptoms include redness, itching, and burning in the eye area or in its surrounding structures, such as the eyelids. Secretion can also occur in some cases, but it is usually more common in the infectious form of the disease.

Risk factors

Anyone, at any age, can develop an allergic process. However, in children allergies are quite common, especially food allergies.

The chances of presenting the condition are also increased by the genetic factor. If there are cases of allergy in family members, it is very likely that you will also develop the disease when you come into contact with the allergen.

Situations that cause low immunity, such as after contracting an illness and during a pregnancy, in addition to factors such as smoking, pollution, infection and hormones, also contribute to the development of allergies.

Allergy symptoms

The signs of allergic conditions vary according to the type of allergy and depend on the substance (allergen) involved. Such symptoms can affect the airways, paranasal sinuses, skin and digestive system.

Respiratory allergies

  • Sneezing;
  • Congested nose;
  • Watery, red or swollen eyes;
  • Nasal itching;
  • Swelling of the mouth and / or respiratory tract;
  • Swollen eyelids;
  • Runny nose.

Skin allergies

  • Swelling;
  • Edema;
  • Itch;
  • Redness;
  • Dry skin;
  • Rash;
  • Itchy skin;
  • Cough, chest tightness, wheezing or shortness of breath (allergy to insect bites).

Food allergy

  • Swelling of the lips, tongue, face or throat;
  • Urticaria;
  • Tingling in the mouth;
  • Diarrhea;
  • Stomachache;
  • Nausea and vomiting.

Drug allergy

  • Itchy skin;
  • Rash;
  • Facial swelling;
  • Wheezing (wheezing).

Eye allergy (allergic conjunctivitis)

  • Swollen eyelids;
  • Watery eyes;
  • Itchy eyes;
  • Red eyes.

How to differentiate: cold, allergy or sinusitis?

A common cold can easily be mistaken for an allergy or sinusitis . However, these conditions can be differentiated by the duration and some symptoms.

The cold usually subsides in a few days, while sinusitis persists for weeks or months. The allergy, on the other hand, usually lasts in proportion to the time of exposure to the allergen.

In addition to allergy-like symptoms (stuffy nose, runny nose, sneezing), the cold can include sore throat , fever and body aches. In the case of sinusitis, the patient usually has a feeling of swelling around the forehead, eyes and cheek; nasal discharge; bad breath ; nausea; cough and fatigue .

It is worth mentioning that sinusitis tends to be a complication of a chronic allergic condition.

When should I see a doctor?

Consult a professional whenever you suspect you are allergic to any substance. This will help to make the correct diagnosis. When you notice symptoms after using a new medication, it is also important to seek medical help.

In cases of more serious reactions, such as anaphylaxis, seek help immediately. In these situations it is important to have regular appointments with a doctor specializing in allergies and immunology.

How is the diagnosis made?

The most recommended doctor to detect the condition is the allergist . The diagnosis is made from the analysis of the patient’s clinical history, together with a physical examination. At this point, it is important to report cases of allergy in the family, since the genetic factor contributes to the appearance of the condition.

In addition, there are some skin tests and blood tests that can confirm whether a person is allergic. Are they:

Skin test

This is the most used method to diagnose allergies. The skin test uses extracts of common allergens (pollen, mites, mold, food) to check the body’s reaction when it comes into contact with such a substance.

There are a few different methods for performing the skin test, but all involve exposing the skin to small amounts of these extracts. One involves applying a plaster that stays on the person for up to 72 hours.

From what is observed, the doctor will indicate the appropriate treatment.

Blood test

The blood test used in the diagnosis of allergy measures the amount of antibodies involved in the allergic process (immunoglobulin E) and present in the bloodstream. The blood sample will be sent for laboratory analysis, being tested for sensitivity to possible allergens.

Food allergy tests

In cases of suspected food allergy, the doctor may request additional tests, such as:

  • Food diary: the patient should write down all the food he eats, as well as meal times. In addition, you should register any allergy symptoms.

  • Elimination diet: consists of eliminating some allergens from the food, and then including them in the diet again, always observing possible reactions. This test is usually performed in conjunction with the food diary.

Is there a cure for allergy? What is the treatment?

Allergy is a treatable disease, but without a cure . Its treatment basically consists of avoiding exposure to allergens and using medications to relieve symptoms.

The doctor may suggest over-the-counter or prescription drugs in the form of pills, tablets, nasal sprays, liquids, eye drops, creams or ointments.

Cases involving more severe reactions may require the application of adrenaline ( epinephrine ). The use happens through injections, which must be purchased under medical prescription.


Also known as desensitization, immunotherapy is a treatment that aims to change the immune system’s response to allergens. The method consists of administering regular doses of allergenic extracts gradually, through injections, sublingual lozenges or drops.

Allergy Medications

Medicines commonly used to treat allergies include:


This type of medication helps to block the release of histamine in the body, reducing allergy symptoms. They are usually used to treat allergic rhinitis or hives.

  • Bronfeniramine: Descongex Plus , Bialerge , Dimetapp ;
  • Cetirizine: Zyrtec , Cetihexal , Reactine , Aletir , Cetirtec , Cirleg, Zetalerg ;
  • Clemastina: Agasten ;
  • Desloratadine: Esalerg , Sigmaliv , Deslorana , Destadin , Desalex D12 , Histabloc , Aleradine ;
  • Diphenhydramine: Difenidrin , Tossilerg ;
  • Fexofenadine: Allegra , Allegra Pediatric , Allexofedrin , Altiva , Rafex , Fexodane , Fexoliv ;
  • Hydroxyzine: Droxy , Pergo , Hixilerg , Hydroxine , Drotizin , Marax , Prurizin , Hixizine , Hydroalerg , Drixi, Hydroxyzine Hydrochloride ;
  • Levocetirizine: Zyxem , Zina ;
  • Loratadine: Clarilerg , Claritin , Loratamed , Alergaliv , Neo Loratadin , Histamix , Cloratadd , Atinac , Clistin , Lergitec , Loradine , Loralerg , Lorasliv , Loremix , Loritil .


Corticosteroids or corticosteroids are sometimes used to treat severe allergies. They can be presented in oral versions, ointments, creams and eye drops.

  • Cortisone acetate: Florinefe , Desaxon , Alergolon , Solu Pred, Neodex ;
  • Dexamethasone: Maxidex , Duo Decadron , Koidexa , Cortidex , Dexanom , Acetazone , Bexeton , Dexaglos , Dexameson ;
  • Hydrocortisone: Cortison , Stiefcortil ;
  • Methylprednisolone: Depo Medrol , Unimedrol ;
  • Prednisolone: Pred Fort , Pred Gran , Prednisolon , Rifocort;
  • Prednisone: Meticorten , Corticorten , Alergcorten , Flamacorten .

Nasal sprays

Effective in the treatment of moderate to severe allergic rhinitis, nasal sprays should be used appropriately, according to medical advice. Its use relieves congestion, runny nose and other allergy symptoms.

  • Azelastine: Dymista , Rino Lastin ;
  • Budesonide: Noex , Budecort Aqua ;
  • Ciclesonide: OMNARIS ;
  • Fluticasone Furoate: Avamys ;
  • Mometasone Furoate: Nasonex ;
  • Oxymetazoline: Freenal .


NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained in this website is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.

Living together

Knowing that the allergy will always be triggered after exposure to the allergen, it is important to take steps to prevent a reaction frame from appearing. Of course, some situations are quite difficult to avoid, such as contact with pollen for example, but a few simple tips can make the patient’s day-to-day easier.

At home

  • Keep humidity below 50% to prevent mold growth;
  • Clean more closed areas that are prone to mold, such as basements and garages. Preferably, ask a non-allergic person to perform the task;
  • Install air dehumidifiers around the house;
  • Avoid leaving wet clothes in the washing machine;
  • Wash curtains and bathroom tiles with anti-mold solutions;
  • Change the bedding weekly and wash it with hot water;
  • Do not allow anyone to smoke inside the house;
  • When cleaning or vacuuming the home, use masks and gloves;
  • Avoid using rugs. Give preference to wooden floors;
  • Install an exhaust fan above the stove to remove cooking vapors.


  • Avoid walking in wooded areas or gardens;
  • Wear a mask when in green areas;
  • Upon returning from a walk, take a shower and wash your hair in order to remove pollen remnants;
  • Protect yourself from insect bites by wearing closed shoes, pants and long-sleeved blouses. Avoid using perfumed deodorants, perfumes, shampoos and other hair products;
  • Always carry the adrenaline injector kit with you, in case you have severe allergies and there is a medical prescription;
  • Avoid hanging clothes or sheets to dry outside, as they can collect mold and pollen.

On trips

  • If so, load your medications in your hand luggage;
  • Always take an extra supply of medication;
  • In hotels, ask for featherless pillows. Preferably take yours in the luggage.

In restaurants

In cases of food allergy, read the menu carefully and ask how to prepare the chosen dish. Always opt for fresh, rather than processed foods.

At school

  • Communicate teachers and staff about the child’s allergic condition;
  • As soon as possible, explain to the child about your allergies, so that he or she can avoid contact with the allergen;
  • Always advise that the child is using medication and make sure that the school has extra doses in case of emergency;
  • Create a kind of card containing all the information about the child’s allergy (symptoms, reactions, names of medicines, medical contact).

Skin allergies: what to do to relieve symptoms?

Some measures can be taken as soon as the symptoms (spots, rashes, redness, etc.) appear on the skin. Follow these steps:

  1. Wash the area with plenty of water and neutral pH soap;
  2. Spread over the area moisturizing creams / lotions with calming action, in order to relieve discomfort and moisturize the skin. Always check if the product is hypoallergenic;
  3. Use thermal water to reduce itching and irritation (optional).


Anaphylaxis (anaphylactic shock)

In rare situations, an allergic reaction can trigger a potentially fatal condition, called anaphylaxis or anaphylactic shock. This severe reaction occurs in a generalized way due to the excess of release of substances and antibodies by the organism, after the contact with the allergen.

Anaphylaxis requires immediate treatment and, in most cases, is quickly reversed by an injection of adrenaline. People who have had the condition are more likely to develop it again. Anaphylaxis cases in the family also favor its onset.


Quite common, asthma is a type of chronic disease that causes the airways to become inflamed, making it difficult to breathe. The condition can be caused by allergens such as pollen, chemicals, climate change, smoke, dust mites, exertion and exercise. Upon contact with such substances, there is swelling, mucus production and narrowing of the airways.

People who have allergic rhinitis usually develop asthma.


Sinusitis is an inflammation of the paranasal sinuses that affect the mucosa of the face. The condition causes symptoms such as headache , runny nose, swollen face, sore throat, nausea and even fever.

In the case of people who have allergies, especially those who have allergic rhinitis, the disease can manifest itself as allergic fungal sinusitis .

Chronic allergy conditions can also cause:

  • Eosinophilic esophagitis : inflammation of the esophagus – channel that leads the food to the stomach. It can cause difficulty to swallow, hoarseness, sore throat and cough;
  • Allergic Bronchopulmonary Aspergillosis : lung disease that can occur in patients with asthma, caused by a reaction to the fungus species Aspergillus. In the list of symptoms and signs are tiredness, fever, cough and obstruction of the airways;
  • Chronic Obstructive Pulmonary Disease (COPD) : set of diseases that lead to pulmonary dysfunction, characterized by difficulty in breathing. It can manifest itself through chronic cough, fatigue and shortness of breath – especially after performing daily tasks;
  • Churg-Strauss Syndrome (SCS) : autoimmune disease that causes inflammation in the blood vessels and is related to asthma;
  • Food Protein-Induced Enterocolitis Syndrome (FPIES) : allergic reaction of the gastrointestinal system that can progress to dehydration and hemorrhagic shock;
  • Gastroesophageal Reflux Disease : a condition that causes gastric juice to escape from the stomach and reach the esophagus, causing irritation in the mucosa. Symptoms include indigestion, burning in the chest, nausea, vomiting and coughing;
  • Hypereosinophilic Syndrome : a rare disease that generates an excess in the production of eosinophils (defense cells), causing lesions in certain organs, such as the heart. It can manifest itself through dermatological symptoms (angioedema, pruritus), hematological symptoms (anemia, thrombocytopenia), gastrointestinal symptoms (diarrhea, nausea, abdominal cramps), among others;
  • Systemic mastocytosis : a disease that generates the proliferation and accumulation of mast cells (connective tissue cells) in the skin and internal organs, causing dysfunctions in the body. Symptoms include skin lesions, itching, sweating, hypotension, tachycardia, nausea, vomiting, etc.

Allergy: Myths and Truths

Myth: Allergies are harmless

Truth: When not treated correctly, allergies can directly interfere with the patient’s quality of life. In addition to the possible complications mentioned above, certain types of conditions, such as allergic rhinitis, result in poor sleep quality, daytime sleepiness and, consequently, learning difficulties and unproductivity.

Myth: Moving to another region can cure allergies

Truth: The climate in each region can interfere with allergic reactions, especially in people with allergies to pollen. However, moving away from these allergens through a change does not promote healing, it only provides temporary relief. That’s because allergic people tend to develop new allergies over time.

Myth: Maintaining daily contact with the animal reduces allergy

Truth: In cases of allergy to pets, sensitivity is usually worsened by continuous exposure. Therefore, the best way to relieve symptoms is to avoid contact with the pet, keeping it out of the house or as far away as possible. Regular baths in the animal are also important.

It is also worth mentioning that even without having a pet at home, it is possible to develop allergic reactions, since the hair and other allergens from animals can be transported in clothes.

Myth: Nasal sprays are not bad for your health

Truth: The use of nasal sprays or decongestants is common in the treatment of allergic rhinitis. However, these drugs should not be used indiscriminately, as they lead to addiction and can cause several health problems including hypertension, cardiac arrhythmia and insomnia .

Myth: Allergies in children disappear over time

Truth: Some types of allergies, especially food allergies, are common in children. Allergic reactions to milk, for example, usually disappear as soon as the child enters kindergarten. However, allergies to other substances, such as peanuts, can persist for life.

Myth: It is not possible to eliminate dust mites from the house

Truth: Generally, dust mites are present in greater quantities in carpeted rooms and houses where there are domestic animals. Therefore, it is important to keep the place, as well as the bedding, mattresses and pillows always clean. This will help to reduce the number of allergens.