How Does an Allergic Reaction Develop?

When a person who is prone to allergies comes into contact with an allergen, their immune system produces specific antibodies known as Immunoglobulin E (IgE). This process is called sensitisation. Upon subsequent exposure to the same allergen, the IgE antibodies that have already been produced recognise it rapidly and signal specialised cells in the body to release chemical substances. One of the most important of these is histamine, which is responsible for many familiar allergy symptoms, including redness, itching, swelling (oedema), and increased mucus production.

What Are the Most Common Allergens?

Allergens can be divided into several categories depending on how a person is exposed to them:

• Airborne allergens: Pollen from trees, grasses and weeds, house dust mites, moulds, and pet dander.
• Food allergens: Milk, eggs, nuts, fish, shellfish, wheat, and soy.
• Medications: Antibiotics (e.g. penicillin), non-steroidal anti-inflammatory drugs (NSAIDs), and others.
• Insect stings: Venom from bees and wasps.
• Contact allergens: Nickel, fragrances, and chemical ingredients found in cosmetics.

What Are the Symptoms of an Allergic Reaction?

Symptoms vary depending on the part of the body affected by the allergic reaction:

• Upper respiratory tract and eyes: Sneezing, runny nose, nasal congestion, and itching of the nose and eyes (Allergic Rhinitis / Allergic Conjunctivitis).
• Lungs: Coughing, wheezing, and shortness of breath (Allergic Asthma).
• Skin: Redness and intensely itchy rashes (Urticaria/Hives), as well as dryness and inflammation (Atopic Dermatitis / Eczema).
• Digestive system: Abdominal pain, nausea, vomiting, and diarrhoea, particularly in food allergies.
• Anaphylaxis: The most severe and potentially life-threatening form of allergic reaction. It can affect several organ systems at the same time and requires immediate medical attention.

Why Do We Develop Allergies?

Allergies develop as a result of a combination of factors, with genetic predisposition (atopy) being one of the most important. In simple terms, when one or both parents have allergies, the likelihood of their child developing an allergic condition is increased.

Environmental factors also play an important role. These include air pollution, aspects of the modern lifestyle such as increased consumption of processed foods, antibiotic exposure early in life, and reduced exposure to a diverse range of microorganisms during childhood, particularly as an increasing proportion of the population lives in large urban environments. These factors may influence the development and regulation of the immune system and contribute to the development of allergic diseases.

How Are Allergies Treated?

Maintaining the allergic patient’s quality of life is a primary goal of treatment. Modern Allergology aims to achieve effective symptom control through a comprehensive treatment plan based on three main approaches.

The first is allergen avoidance. Once the responsible allergens have been identified through appropriate diagnostic testing, specific measures can be taken to reduce exposure to them.

The second is medication, which may include antihistamines, corticosteroid nasal sprays, inhaled medications, or other treatments used to control and relieve allergic symptoms.

Finally, Allergen Immunotherapy (allergy shots / drops / tablets) is the only disease-modifying treatment that targets the underlying allergic response rather than simply relieving symptoms. By gradually exposing the immune system to controlled amounts of the responsible allergen, immunotherapy helps the body develop tolerance to it. This can provide significant and long-lasting improvement in allergic symptoms and reduce the need for medication.

In conclusion, if you suspect that you or a member of your family may be experiencing allergic symptoms, they should not be ignored. An appropriate allergy assessment, including specialised skin tests and/or blood tests, can provide clear answers, identify the responsible allergens, and guide the selection of the most appropriate treatment.

For more information or to schedule an allergy assessment, please contact our clinic.

Το άρθρο When the Immune System “Gets It Wrong” εμφανίστηκε πρώτα στο Allergist Alexandroupoli.

Allergic rhinitis is one of the most common chronic conditions, affecting approximately 1 to 3 in 10 adults and more than 4 in 10 children worldwide. It is a non-infectious inflammation of the nasal mucosa caused by an exaggerated immune response to airborne allergens such as pollen, house dust mites, and animal dander. When exposed to these allergens, immune cells are activated and release histamine and other inflammatory substances, resulting in vasodilation (widening of the blood vessels) and swelling of the nasal mucosa. This swelling, together with irritation of nerve endings and increased mucus production, contributes to the characteristic feeling of nasal congestion or a “blocked nose” commonly experienced by patients with allergic rhinitis.

In clinical practice, allergic rhinitis is classified according to when symptoms occur and their severity. Seasonal allergic rhinitis occurs during specific periods of the year and is mainly caused by pollen from trees (such as olive and cypress), grasses, and weeds (such as Parietaria). In contrast, perennial allergic rhinitis persists throughout the year and is associated with allergens such as house dust mites, moulds, and pet dander, particularly from cats and dogs.

Depending on the frequency of symptoms, allergic rhinitis can also be classified as intermittent (symptoms occurring fewer than 4 days per week or for fewer than 4 consecutive weeks per year) or persistent (symptoms occurring more than 4 days per week and for more than 4 weeks). Finally, according to the impact of symptoms on the patient’s daily life, allergic rhinitis may be classified as mild, moderate, or severe.

Typical symptoms include paroxysmal sneezing (repeated episodes of sneezing), clear nasal discharge, intense nasal itching, and nasal congestion. Allergic conjunctivitis frequently occurs at the same time, causing excessive tearing, redness, and itching of the eyes. Patients may also experience postnasal drip (mucus draining towards the throat), coughing, and dry mouth due to the need to breathe through the mouth. In some cases, dark circles may develop under the eyes as a result of chronic venous congestion associated with impaired nasal breathing.

In addition, a significant proportion of patients with pollen allergy may develop pollen-food allergy syndrome (PFAS), also known as oral allergy syndrome (OAS). This condition causes itching or swelling in the mouth after eating certain raw fruits, vegetables, or nuts containing proteins that are structurally similar to proteins found in pollen.

Allergic rhinitis is often confused with the common cold or non-allergic rhinitis, but there are important differences. The common cold is a viral infection that is often accompanied by fever, fatigue, muscle aches, and thicker nasal secretions, with symptoms usually resolving within 5–10 days. In contrast, allergic rhinitis does not cause fever and persists for as long as exposure to the responsible allergen continues. Itching inside the nose is also a particularly characteristic symptom.

If allergic rhinitis remains undiagnosed or inadequately treated, it may contribute to the development of associated conditions such as chronic sinusitis, nasal polyps, and otitis media with effusion in children. In addition to causing sleep disturbances, allergic rhinitis is also associated with an increased risk of developing allergic asthma, which affects the lower respiratory tract and may cause symptoms such as coughing, shortness of breath, and wheezing.

An accurate diagnosis can be established at the allergy clinic through skin prick tests, a quick and virtually painless procedure that provides results within just 15–20 minutes, or through specific blood tests measuring allergen-specific IgE antibodies.

Treatment is always tailored to the individual patient and may include second-generation antihistamines, which generally cause little or no drowsiness, to control sneezing, itching, and nasal discharge. At the same time, intranasal corticosteroids (nasal sprays) are among the most effective treatments for reducing inflammation and nasal congestion.

Particular caution is required with commercially available decongestant nasal sprays containing vasoconstrictor agents. Excessive use for more than 3–5 days may lead to rhinitis medicamentosa (rebound congestion), a condition in which the nasal mucosa becomes increasingly swollen once the effect of the medication wears off, leading to repeated and potentially prolonged use.

Finally, the only disease-modifying treatment that goes beyond temporary symptom relief and targets the underlying allergic response is Allergen-Specific Immunotherapy (AIT), also known as desensitisation. Through the regular administration of controlled amounts of the responsible allergen—either sublingually as drops or tablets (SLIT) or through subcutaneous injections (SCIT)—the immune system is gradually trained to develop tolerance to that allergen.

Allergen immunotherapy can provide long-term improvement in symptoms, substantially reduce the need for medication, and may reduce the risk of progression from allergic rhinitis to asthma in appropriately selected patients.

If you experience persistent or recurrent nasal symptoms, an allergy assessment is an important first step towards identifying the underlying cause and restoring your quality of life.

Do you have symptoms consistent with allergic rhinitis? Contact our clinic to schedule your appointment.

Το άρθρο Seasonal and Perennial Allergic Rhinitis εμφανίστηκε πρώτα στο Allergist Alexandroupoli.

The procedure is performed in the doctor’s office within just a few minutes and involves a series of specialised, standardised, high-purity allergen extracts. The allergist places small drops of these extracts on the inner surface of the forearm and then uses a special, microscopic metal lancet to apply gentle pressure to the surface of the skin through each drop. This pressure is barely noticeable, does not penetrate deeply, and does not pierce the skin in the same way as an injection. Instead, it feels more like a brief, mild prick.

The safety of skin prick testing is well established. The test accurately reproduces the body’s allergic response on a much smaller, localised scale in the skin. The amount of allergen introduced into the superficial layer of the skin is minimal and acts locally, without entering the bloodstream. This means that the risk of a systemic or severe allergic reaction is practically negligible, while any itching and swelling usually subside spontaneously within a few hours.

Furthermore, the examination is always carried out under the direct supervision of a specialist allergist in a fully equipped and safe medical environment. To ensure maximum reliability of the results and to rule out false-positive or false-negative findings, the doctor simultaneously uses **control substances**: histamine as a positive control (to confirm that the skin is responding normally) and saline solution as a negative control.

The range of allergens tested is comprehensive and covers a broad spectrum of environmental factors responsible for respiratory allergies. Specifically, the categories of allergens examined include **tree pollens** (such as olive, cypress, plane tree, etc.), **grass pollens and weed pollens** (such as *Parietaria*), **house dust mites**, **moulds** (both indoor and outdoor), as well as **pet dander and epithelial allergens** (including cat and dog). In the case of a positive result, a **wheal** (mild swelling) develops at the site of the skin prick, often surrounded by redness and mild itching similar to a mosquito bite, helping to identify the responsible allergen.

It is important to note that a positive skin test indicates **sensitisation** of the immune system to a specific allergen; however, this does not automatically mean that the patient has a clinically relevant allergy. For this reason, skin prick tests are always performed in conjunction with a detailed medical history. The final interpretation of the results is made exclusively by the allergist, who evaluates the test findings together with the patient’s medical history and symptoms.

An important requirement before the examination is the discontinuation of **oral antihistamines for 5 to 7 days**, as these medications suppress the skin’s normal response and may affect the test results. Other treatments, such as **corticosteroids (topical preparations), certain antidepressant or sedative medications, topical calcineurin inhibitors, or monoclonal antibodies such as omalizumab**, may also influence the results and may require appropriate planning before testing, according to the allergist’s instructions. Common medications used to treat asthma or rhinitis, such as **inhaled medications or nasal sprays, generally do not affect the test**.

In conclusion, skin prick tests provide a rapid, safe, and virtually painless method for identifying the allergens responsible for a patient’s symptoms. When interpreted together with the patient’s medical history, the results help guide the selection of an appropriate and targeted treatment plan.

*Do you have symptoms that may be related to a respiratory allergy? Contact our clinic to schedule your allergy assessment.*

Το άρθρο Skin Prick Tests (SPTs) εμφανίστηκε πρώτα στο Allergist Alexandroupoli.