Which inflammatory mediator is primarily responsible for causing swelling, redness, and warmth following an injury?

Histamine plays a crucial role in the inflammatory response, particularly during the early stages following an injury. It is released primarily by mast cells and basophils and acts to increase the permeability of blood vessels. This increased permeability allows plasma and other fluid components to escape into the surrounding tissue, leading to swelling (edema) and redness due to enhanced blood flow. Additionally, histamine causes vasodilation, which contributes to the warmth and redness often observed in inflamed areas.

The release of histamine is part of the body's immediate response to injury, emphasizing its significance in initiating the inflammatory process and facilitating healing. Understanding the primary actions of histamine helps clarify its central role in the clinical manifestations associated with inflammation.