Banner by Rajvi Desai

Leeches, Fevers, and Fleams: The Evolution of Bloodletting  

by Julia Feibusch 

Imagine going to your doctor for a sore throat and finding yourself being bled of the very fluids necessary for your survival via lacerations or parasitic worms. In the winter of 1799, doctors drained George Washington of over 80 ounces of his blood to treat his fever and pain in his throat. He lost approximately 40% of his blood in the span of 12 hours. It is a commonly held belief that George Washington died from hypovolemic shock due to excessive bloodletting. Rather, Washington most likely died from acute epiglottitis, a bacterial infection of the epiglottis—though the bloodletting certainly did not help. The immense blood loss likely exacerbated his condition. Dr. Howard Markel, a medical historian, states that “if the disease itself didn't get George Washington, the doctors certainly did.” So why did doctors drain him of 40% of his blood? Bloodletting was the standard of care at the time, justified by a long medical tradition of humoral theory that dates back to ancient Greece and Egypt. Washington even requested the treatment. While bloodletting is not widely used today, there are still some medically appropriate uses.  

Bloodletting originated in ancient Egypt, with evidence of the medical practice in texts as early as 1550 B.C. The Ancient Greeks continued this practice with both Hippocrates (460–370 B.C.) and Galen (129–200 A.D.) developing and popularizing humoral theory, the belief that the human body is made of four humors, or fluids: blood, phlegm, yellow bile, and black bile. Humoral theory became the foundation of bloodletting and much of Western medicine into the nineteenth century. An imbalance of the humors was believed to be the cause of illness. This concept of bodily equilibrium dominated people’s understanding of health and disease in the era of pre-scientific medicine. Because of this, there was significance placed on the output of measurable fluids like blood, urine, and even sweat. Without proper diagnostic testing, physicians relied on methods that provided visual clues to monitor health and pharmaceutical interventions. This led to the development of therapies to balance the humors and bring the body back into equilibrium, usually through the extraction of excess humors. Common treatments included dietary changes and emetic drugs to induce vomiting, though none of these methods are as infamous as bloodletting. 

A variety of tools and methods were used for bloodletting, the removal of excess blood thought to be causing the humor-imbalance related illness. These tools were used to treat various illnesses and conditions, ranging from fever and inflammation to epilepsy and gout. Most commonly, a vein at the elbow would be bled, often using a tool called a fleam. Similar to a pocket knife, a fleam was a device with three different blades that could be used on adults, children, and even livestock. A physician could treat a whole family and their farm with just one small tool.  

Bloodletting using the medicinal leech, Hirudo medicinalis, was also commonly practiced. The use of leeches dates back to the time of Galen. Medicinal leeches have saliva with anticoagulant and anesthetic properties, and they can ingest almost ten times their body weight in blood. This made them well-suited for the practice of bloodletting and less invasive than other methods. Leeches became increasingly popular in Europe, particularly in France, creating a “leech mania” in the early 1800s when they became a sought-after commodity. After demand led to the overharvesting of leeches from the country’s marshlands, France imported 50 million leeches in 1832 alone. Bloodletting with leeches was even a service offered in barbershops. “Leech boxes” and “leech jars” became fashionable for holding live leeches. They varied from small pewter boxes to more decorative and ornate ceramic pieces. This mania and the broader practice of bloodletting began to subside with the growth of scientific medical practices in the mid-to-late 1800s. Studies disproving the efficacy of bloodletting, along with the advent of germ theory, ultimately led to the decline of the practice. 

Bloodletting is no longer seen as a cure-all; however, the practice has a few evidence-based uses today. The modern practice of bloodletting is now called therapeutic phlebotomy, which is the drawing of blood to treat various illnesses. Much less gruesome than a fleam, a needle is now used, and the process is similar to donating blood. This is most commonly done to treat the blood disorders hemochromatosis and polycythemia vera. Hemochromatosis is a condition where the body absorbs too much iron, which accumulates and damages organs, particularly the liver. The treatment involves periodic phlebotomy, or the removal of blood regularly to reduce iron levels. Polycythemia vera is a blood cancer causing the bone marrow to overproduce red blood cells, which leads to the thickening of blood and increases the risk of clots. Management of the disease is similar to hemochromatosis, consisting of regular phlebotomy with the frequency of withdrawals depending on severity of disease. Removing blood decreases the excess of red blood cells and reduces the risk of clotting.  

Medicinal leeches, perhaps the most unsettling of the historical methods of bloodletting, are still used today in microsurgery and reconstructive surgery fields. They are particularly useful in aiding reattachment of tissues such as fingers and toes. Through active chemicals in their saliva, such as hirudin, leeches promote anticoagulation, encouraging blood flow to digits, facial tissue, and skin flaps for reimplanted tissue. This alleviates venous congestion, the pooling of blood which can lead to blood clots and tissue death. Although the rationale and understanding of the practice has changed drastically, leeches are still used in advanced medical practices, five millennia after its first documentation. 

Without modern tools like imaging and blood tests, bloodletting seemed logical in a world where observable metrics like blood and urine were the only indicators of treatment efficacy. The practice became deeply embedded into medical tradition as it fit within people’s worldviews. With the evolution of technology, this long-standing tradition was challenged, leading to a shift towards more evidence-based practices. There is a tendency to dismiss historical practices and people as unintelligent, foolish, or even barbaric. Rather than dismissing past practices, examining the historical, social, and scientific framework that supported them provides insight into why such practices were so pervasive. There is much to learn from antiquated medical traditions, some of which, like bloodletting, might have unexpected value today. Looking back on George Washington, his treatment serves as a reminder of just how far modern medicine has come and underscores the progress science has made in leaving humoral theory behind. So next time you have a fever and sore throat, take comfort when your doctor hands you a nasal swab kit instead of lifting the lid to a decorative leech box.