Which condition results in the body’s response of redness and swelling without involving an infection?

The body's response of redness and swelling without involving an infection is best characterized by inflammation. Inflammation is a complex biological response that occurs when tissues are damaged or irritated, resulting in a protective mechanism aimed at removing harmful stimuli and initiating the healing process. This response is marked by various physical signs, including redness (due to increased blood flow), swelling (from fluid accumulation), heat, and pain.

While irritation can lead to some localized redness or swelling, it typically does not encapsulate the full biological processes and systemic responses that inflammation encompasses. Dermatitis is a specific type of inflammation that particularly refers to skin conditions, often caused by allergens or irritants, but again, it is a subset of inflammation rather than a condition that describes the response itself. Edema refers specifically to an accumulation of fluid in tissues, which can sometimes accompany inflammation but is not synonymous with the inflammatory process itself. Thus, inflammation as a broader term accurately captures the body's response characterized by these signs, differentiating it from other related terms.