C5a anaphylatoxin is a potent inflammatory mediator in the complement system. It is generated during the cleavage of complement component C5. With a relatively small molecular weight, C5a possesses remarkable biological activities. It acts as a chemoattractant, drawing various immune cells like neutrophils, monocytes, and eosinophils to the site of inflammation. Additionally, C5a can activate these immune cells, enhancing their phagocytic ability and promoting the release of inflammatory cytokines and chemokines. Moreover, C5a plays a role in increasing vascular permeability, which facilitates the migration of immune cells and plasma proteins from the bloodstream to the inflamed tissue. Dysregulation of C5a has been implicated in numerous inflammatory and autoimmune diseases, making it a crucial target for therapeutic interventions.