Allergen

An allergen is a substance that can trigger an immune system response in some individuals. When someone with allergies encounters an allergen—such as certain foods, pollen, pet dander, or dust mites—their immune system mistakenly identifies it as dangerous and releases chemicals like histamine. This reaction can cause symptoms like sneezing, itching, swelling, or more serious reactions like difficulty breathing. Allergens vary from person to person, and avoiding exposure or managing reactions with medication can help individuals with allergies maintain better health and comfort.