Allergy - causes and symptoms, how to treat allergy?

Speaking of allergies, we often don't realize that it is currently one of the most common diseases in the world. According to studies, about 40 percent of us suffer from it, and the number of patients continues to grow. So it's worth knowing what allergy is, why we suffer from it and can it be cured?

Allergy, and allergens

Nowadays, allergy is defined as a disease that develops due to an erroneous reaction of the immune system to substances that are generally not harmful to us. The body's response is triggered by allergens, that is, small, primarily proteinaceous, molecules.
The problem, however, is that an allergen can be almost any substance in the human environment. Its correct identification is the biggest challenge for a doctor.

How do we divide allergens?

Sensitizing substances can be divided into at least several types. However, based on their mode of contact with the body, allergens are most often divided into inhalant and food allergens. In addition, it is also worth distinguishing contact allergens and those found in insect venom and drugs.

• Inhalant allergens

They can be found, for example, in house dust mites, pollen, or mold spores. Also popular in this group are allergens of animal origin. They penetrate our body with the air we breathe in. Once they reach the surface of the nose or throat, they can transfer allergens and allow them to penetrate the mucous membrane and cause a reaction in the body.

• Food allergens

Allergens in foods are natural substances, found mainly in the form of plant and animal proteins. They have been found in all groups of food products. The main ones among them include: cow's milk, egg white, soy, peanuts, gluten-containing cereals, meat, seafood, fish. Allergens can also be found in food additives, i.e. preservatives, dyes or flavor enhancers.

• Contact allergens

When we talk about contact allergens, we mean chemical compounds, most of which are haptens. These substances become full-fledged allergens only after binding to epidermal proteins. In direct contact with the skin, they cause various types of irritation.
Although there are known approx. 4000 chemicals that exhibit allergenic effects, the most common allergens in this group are metals, preservatives, plastics and fragrances.

• Insect venoms

In Central Europe, most allergies to insect venom are caused by honeybees less frequently by wasps, hornets or bumblebees. A group of people particularly vulnerable to stings because of their work are beekeepers.
Not every reaction to an insect sting indicates an allergy and requires medical intervention. Normal symptoms can include: erythema, swelling and pain at the site of the sting, lasting a maximum of 24 hours. If these symptoms are also accompanied by skin reactions (swelling, itching, hives and angioedema), respiratory (coughing, shortness of breath), gastrointestinal (abdominal pain, diarrhea), cardiovascular (drop in blood pressure, heart disorders), then we can assume that we are dealing with an allergy to insect venom.

• Allergens in medicines

An allergic reaction can be triggered by virtually all known medicinal substances, although some cause them with greater frequency. Among the more frequently sensitizing drugs are penicillin, amoxicillin and various drugs from the group of non-steroidal anti-inflammatory drugs, such as metamizole, tramadol and others.

Causes of allergies, are genes to blame?

Scientists have been trying for years to answer the question of what causes allergies and whether genes are involved in their onset. Put simply, do we inherit allergies from our parents. According to researchers, we do not inherit the disease itself, but a certain propensity to develop it does. What does this mean? Statistically, the probability of allergy in a child of healthy parents is determined at 15 percent. If one of them has an allergy, the risk of the disease increases to 30-40 percent. If both parents are ill, the probability of allergy in a child is determined at 60-80 percent.

However, scientists point out that environmental factors have a greater impact on the onset of allergic diseases. What can be counted among them? Lifestyle changes, the type of food consumed, exposure to second-hand smoke, in all likelihood also environmental contamination, excessive hygiene and antibiotics taken too often.

Allergy symptoms

It is worth noting right away that allergy is not the same as sensitization. We speak of it only when allergic people also have symptoms. What symptoms, then, can suggest an allergy?

The most common of these are: runny nose, sneezing, nasal congestion and itching, watery and red eyes, conjunctivitis, rash, severe itching and dry skin, shortness of breath, wheezing, itching and burning of the lips and palate, nausea, vomiting, abdominal pain, diarrhea. Depending on the type of allergy, only some of the above symptoms may be present.

Allergies can sometimes also manifest as anaphylactic shock, which is an immediate life-threatening condition. It is characterized by a drop in blood pressure, loss of consciousness, and shortness of breath.

Cross-reactions

We start thinking about them when allergy symptoms appear in us after contact with an allergen to which we were not originally allergic. So it happens that we have, for example, a diagnosed allergy to birch pollen, and we feel symptoms after eating an apple. In such a situation, a cross-reaction, i.e. a misidentification of the allergenic substance by our immune system, may be just happening. Why does this happen? Because many allergens have a similar structure. If the similarity exceeds 70 percent, then the occurrence of a cross reaction is very likely.
Interestingly, such reactions are not at all rare. It turns out that up to 60 percent of food allergy symptoms are not at all caused by the food we have eaten, but can be associated with hypersensitivity to pollen.
So it is worth knowing which allergens most often cross-react with each other. This type of reaction often occurs between:

• pollen vs. foods, for example, people who are allergic to birch pollen may have symptoms after eating apple, cherry, peach, pear, parsley, celery or almonds
• latex vs. fruit
• cat allergens vs. pork
• house dust mite and seafood, primarily shrimp

Allergy diagnosis methods

Making a proper diagnosis in the case of allergies often involves many difficulties. The key is to find the substance that sensitizes us. Diagnosis begins with a visit to the doctor. The specialist will conduct a thorough interview with the patient. He will ask about the symptoms present, family history of allergic diseases, but also about our lifestyle, meals consumed or leisure activities. The information gathered will be the basis for further diagnosis.

If the doctor suspects an allergy, he will have the patient tested accordingly.

Among the studies ordered may be:

• Spot skin tests - these are usually carried out on the skin of the forearms or back. During the test, a drop of alFergen solution is placed on the skin. The person performing the test (usually a nurse) then pricks the skin, through the drop of allergen, with a special lancet. The results are read after several minutes - in the case of epidermal spot tests and after 48 hours after patch tests.

• Blood tests - are performed by drawing a small amount of blood from the patient. They consist in determining the concentration of serum E antibodies against specific allergens. When performing blood tests, sets of allergens called panels are used (e.g. inhalant, food, pediatric, atopic or respiratory). You can also use the so-called multiplex tests, which allow you to check the concentration of E antibodies against up to nearly 300 molecules and allergens in a single test(^Alex2 test). Very importantly, thanks to molecular diagnostics, the doctor is able to accelerate the diagnosis, assess the possibility of severe allergic reactions and cross-reactions. This type of diagnostics is also helpful in qualifying patients for desensitization (immunotherapy).

• Provocative tests - natural allergens, such as food, are used to conduct these tests. By giving the patient a small amount of the product, the onset of symptoms is observed. Very importantly, this type of testing is carried out under medical supervision, usually in a hospital.

Can allergies be cured?

If we already know we have an allergy, we often have to change our lives quite radically. The most important thing will be to eliminate the allergen from our diet or environment. If this is not possible, we must try to reduce our contact with allergenic substances as much as possible. If symptoms worsen, the doctor will prescribe appropriate medications, most often glucocorticosteroids and antihistamines.

In contrast, the only method of treating the cause of allergies is immunotherapy. It involves the safe administration of an extract containing the allergens to which the patient is allergic. In this way, our immune system learns to tolerate these substances. Immunotherapy is always conducted under the supervision of an experienced specialist. This type of therapy usually lasts from 3 to 5 years.

Not every person with allergies can benefit from immunotherapy. In Poland, patients allergic to pollen (grass, birch, alder, hazel, mugwort), mold (Alternaria), house dust mite and insect venom (wasps, bees) can be treated with this method. Less commonly, immunotherapy is used for animal allergens (cat and dog).

Types of immunotherapy:

• Subcutaneous involves the administration of appropriate doses of allergen extract in the form of injections, first on a weekly and then on a monthly basis.
• Sublingual immunotherapy can be administered using drops or tablets. The initiation of treatment is carried out in the office of a specialist, and then the patient continues with subsequent doses independently at home.