An allergy is an abnormal reaction of the immune system to normally harmless substances. In the presence of an allergen , the immune system produces specific antibodies, immunoglobulin E (IgE), which trigger the release of histamine and other chemical mediators. This mechanism underlies allergic symptoms, which can range from mild symptoms, such as itching or sneezing, to more severe reactions such as anaphylaxis, a potentially life-threatening medical emergency.
Allergies are particularly common in spring. Professor Enrico Heffler , Head of the Personalized Medicine Center: Asthma and Allergology at the IRCCS Istituto Clinico Humanitas Rozzano and allergist at Humanitas Medical Care, will discuss the symptoms of allergies and what tests are needed for diagnosis.
What causes allergies?
Allergies are caused by an excessive immune response to specific allergens. Among the most common are:
- inhalant allergens such as pollen, animal dander, dust mites, mold
- food allergens such as milk, eggs, fish, shellfish, peanuts, tree nuts, wheat, soy
- drugs , such as antibiotics, analgesics, anesthetics
- insect venoms , such as bee and wasp stings
- chemicals and materials , from latex to nickel.
Seasonal allergies in Italy are mainly triggered by pollen, including
- Birch (February-April, especially in Northern Italy)
- Olive (mid-spring, prevalent in Mediterranean regions)
- Graminaceae (March-June, widespread in both the North and the South)
- Parietaria (present for many months in Mediterranean areas)
- Ambrosia (August-October, typical of the northern regions).
Exposure to these pollens varies depending on the geographic area and the time of year, influencing the onset of allergic symptoms.
What are the symptoms of allergies?
Regardless of the allergen involved, the symptoms of spring allergies are generally the same. Among the most common:
- Allergic rhinitis: runny nose, sneezing, nasal itching, congestion
- Allergic conjunctivitis : red eyes, tearing, itching
- Allergic asthma : shortness of breath, dry cough, chest tightness.
Many symptoms can be confused with those of a common cold, but while a cold resolves spontaneously within a few days, an allergy persists for weeks or months, as long as exposure to the allergen continues.
Allergy visit and prick test for diagnosis
Even adults who have never suffered from allergies can develop them over time. For a precise diagnosis, an allergy consultation is recommended , during which the specialist can prescribe specific tests to identify the responsible allergens.
- Prick Test : A first-level test for inhalation and food allergies. Allergen extracts are applied to the skin of the forearm and a small, superficial prick is performed. If a reaction (wheal and redness) occurs, the test is positive.
- Blood tests : These measure the presence of specific IgE antibodies to certain allergens and are useful in cases where a prick test is not indicated, for example, if the patient takes antihistamines or has particularly reactive skin. It is also possible to perform a test to evaluate a very large number of allergens (295 in total) with assessment of sensitization at the level of the individual molecules that compose them: this is the ALEX Test, very useful especially for patients with numerous sensitivities.
Allergies: how are they treated?
Allergy treatment can involve several therapeutic options.
- Antihistamines : Available in tablet form, they reduce itching, sneezing, and nasal congestion. Newer formulations cause less drowsiness than traditional ones.
- Corticosteroid nasal sprays : These help reduce inflammation of the nasal mucosa and are particularly indicated for persistent forms of allergic rhinitis. Long-term use should be under medical supervision.
- Allergen immunotherapy (desensitization) : This is the only strategy that can alter the natural progression of allergic disease. It involves the controlled administration of the causative allergen, in the form of sublingual drops or tablets, for a minimum of three years. This treatment, often referred to as an ” allergy vaccine ,” helps reduce the immune system’s sensitivity over the long term.
