What kind of effects do allergic reactions typically involve?

Allergic reactions typically involve symptoms that manifest primarily in individuals who have a heightened sensitivity or predisposition to specific allergens. When a person is exposed to an allergen, their immune system may overreact, leading to a range of symptoms such as itching, swelling, hives, or respiratory issues. This means that only those who are sensitive will display these symptoms upon exposure, distinguishing allergic reactions from other toxic responses that may affect a wider population.

The context of the other choices is important for understanding the specificity of allergic reactions. Immediate toxicity refers to a rapid toxic response that can occur with certain substances but does not necessarily involve an immune reaction or allergy. Genetic alterations pertain to changes in DNA that can occur due to various factors, including chemical exposure, but not specifically in the context of allergic reactions. Delayed onset symptoms can occur with specific types of hypersensitivity reactions, but they do not represent the typical acute nature of most allergic responses that are characterized by immediate symptoms in sensitive individuals.