Living With Allergies In A Rapidly Changing World
What An Allergy Is: An allergy happens when the immune system reacts strongly to a substance that is usually harmless. These substances are called allergens. Common allergens include pollen, dust mites, pet dander, certain foods, and insect stings. When exposed to an allergen, the body releases chemicals such as histamine. This can cause sneezing, itching, swelling, rashes, or trouble breathing. In severe cases, a reaction called anaphylaxis can occur, which requires immediate medical care.