An allergic reaction occurs when the immune system overreacts to a normally harmless foreign substance. This can manifest with various symptoms such as eye discharge, itching, sneezing, nasal discharge, congestion, shortness of breath, wheezing, abdominal cramps, nausea, diarrhea, fainting, malaise, itchy rashes, and swelling. Identifying the specific allergen causing these symptoms can often be challenging for individuals. To objectively determine the culprit allergen, skin tests are typically performed, correlating with the patient's reported symptoms. In cases where skin testing is not feasible due to various reasons, blood tests are utilized to identify the responsible allergen. Once an allergic disease is diagnosed and the causative allergen is identified by a specialist allergist, and the decision for immunotherapy (allergy vaccination) is made, a personalized treatment plan is developed in collaboration with the patient. It is crucial that the vaccine treatment begins when the patient is relatively healthy and the allergic disease is not actively flaring. Immunotherapy works by gradually exposing the individual to very small doses of the allergen they are sensitive to, effectively training the immune system to tolerate it. The initial phase of treatment typically lasts between 6 to 16 weeks, adjusted based on the specific allergen, co-existing medical conditions, and the patient's immune status. During this initial phase, the vaccine is usually administered once a week. The maintenance phase, which follows, requires monthly administration for a period of three years. While commonly administered as an injection in the arm, immunotherapy is also available in oral forms such as drops or tablets.