Reperfusion injury occurs when blood flow is restored to tissues or organs after a period of ischemia (lack of blood supply). This sudden reintroduction of oxygen and nutrients can lead to the generation of reactive oxygen species and inflammatory mediators, causing damage to the previously ischemic tissue. Reperfusion injury is a common complication of treatments such as cardiac bypass surgery, organ transplants, and stroke therapy. Researchers are studying ways to minimize reperfusion injury through strategies such as pharmacological agents, antioxidants, and therapeutic hypothermia.