Which term describes a substance that causes an allergic reaction?

Which term describes a substance that causes an allergic reaction?

• A. A substance that causes a localized inflammatory reaction on contact
• B. A substance that causes an allergic reaction
• C. A substance that increases blood sugar
• D. A substance that suppresses the immune system

Answer: (B)

An allergen is the term for a substance that triggers an allergic reaction. When a person who is allergic encounters an allergen, the immune system may overreact, often involving IgE antibodies and the release of histamine and other chemicals. This can lead to symptoms such as itching, redness, swelling, sneezing, or more serious reactions. This differs from an irritant, which can cause inflammation without an immune-mediated allergy; from something that raises blood sugar, which is a metabolic effect; or from something that suppresses the immune system, which would reduce immune responses rather than trigger them. So the best description for a substance that causes an allergic reaction is allergen.

An allergen is the term for a substance that triggers an allergic reaction. When a person who is allergic encounters an allergen, the immune system may overreact, often involving IgE antibodies and the release of histamine and other chemicals. This can lead to symptoms such as itching, redness, swelling, sneezing, or more serious reactions.

This differs from an irritant, which can cause inflammation without an immune-mediated allergy; from something that raises blood sugar, which is a metabolic effect; or from something that suppresses the immune system, which would reduce immune responses rather than trigger them. So the best description for a substance that causes an allergic reaction is allergen.