Медицинская анимация. Аллергия.

When your childs immune system detects a harmful substance or infection, it responds to protect your childs body. Allergies occur when your immune system reacts to a harmless substance as if it were harmful. An allergic reaction does not occur with the first exposure to the substance, your childs body must have been exposed to it at least once before. After one allergic reaction, further contact with the substance produces another reaction. Substances that produce allergies are called allergens. Common ones include mold, animal dander, dust and dust mites, latex, medicines, insect stings and foods. Some allergens, like mold and pollen, are carried through the air. These allergens cause hay fever, and its symptoms of sneezing, watery eyes, and a stuffy or runny nose. Touching an irritant may cause allergic skin reactions. Common causes of a skin allergy include hair or skincare products, metals in jewelry, such as nickel, fabric dyes, and poison ivy. Symptoms include itching, swelling, and a rash or hives. Allergies can also cause wheezing, stomach cramps and diarrhea.