Which of the following counts as a systemic symptom of an allergic reaction?

Hives, also known as urticaria, are raised, itchy welts on the skin that occur as a result of allergic reactions. While they are often localized, they can indicate a systemic allergic response within the body. When an allergic reaction occurs, the immune system releases histamine and other chemicals, which can lead to the development of hives. This response can be part of a broader systemic reaction, especially if it progresses to more severe manifestations such as anaphylaxis, which affects multiple systems in the body.

In the context of allergic reactions, systemic symptoms are those that indicate the involvement of multiple organ systems rather than just localized effects. Hives, while visible on the skin, serve as an indicator of this systemic involvement because they can show that the body is reacting to an allergen beyond just a localized response.

Other options, like chills, dizziness, and nausea, can certainly arise from various causes, including allergic reactions, but they are not specific indicators of an allergy in the way that hives are. Each of these symptoms can be linked to different physiological or medical conditions, and their presence alone does not definitively confirm an allergic reaction. Instead, they are more generalized responses and might indicate reactions that are not primarily allergic in nature.