Allergy symptoms are typically triggered by the immune system's reaction to substances known as allergens. Common allergens include pollen, dust mites, pet dander, mold spores, certain foods, insect stings, and medications. When your immune system identifies these substances as harmful, it releases chemicals like histamine, which leads to allergy symptoms like sneezing, runny nose, itching, and more. However, the factors responsible for allergy symptoms vary by individual. Consult a medical professional for proper diagnosis ...