Answer:By definition, an allergy is a hypersensitivity immune response to normally harmless substances, such as pollens or foods. For most people, these substances–also called allergens–pose no problem. In allergic individuals, however, the immune system identifies them as a threat and produces an inappropriate response
The symptoms of allergic diseases are numerous and may also be attributable to more than one allergy, as up to 80% of allergic patients are sensitized to more than one allergen.
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