bloodletting

Bloodletting is the withdrawal of blood from a patient for therapeutic purposes. Historically practiced in many cultures, it was often achieved by venesection (phlebotomy), cupping, scarification, or the application of medicinal leeches. The practice was guided by the theory of humors, which held that health depended on the balance of bodily fluids, especially blood. Bloodletting was prescribed for a wide range of conditions, including fevers, inflammation, headaches, and hypertension, among others.

Throughout antiquity and the Middle Ages, and into the early modern period, bleeding was a dominant component of medical care in Europe, the Middle East, and other regions. Prominent physicians such as Galen and later medical authorities incorporated bloodletting into diagnostic and therapeutic routines. With advances in anatomy, physiology, and the germ theory of disease, the perceived justifications for bleeding diminished, and many practices were questioned. By the late 19th and early 20th centuries, bloodletting had declined as a general treatment, though it persisted in specific contexts.

In contemporary medicine, bloodletting survives in limited, evidence-based forms. Therapeutic phlebotomy is used for polycythemia vera to reduce red cell mass and to manage hyperviscosity, and for hereditary hemochromatosis to lower iron levels. Leech therapy (hirudotherapy) is employed in certain surgical settings to improve venous drainage and tissue survival. For most conditions, however, rigorous clinical trials have not supported routine bloodletting, and it is approached with caution due to risks such as anemia, hypovolemia, and infection.