Allergies occur when the immune system overreacts to normally harmless substances in the environment known as allergens. Common allergens that can trigger allergic reactions include pollen from trees, grasses or weeds, dust mites, mold, pet dander and foods. Symptoms of allergies can vary depending on the type of allergen and route of exposure but may include sneezing, itchy/watery ey... https://webyourself.eu/blogs/813107/Innovations-in-Allergy-Diagnosis-and-Treatment