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This week we explore the bizarre — and surprisingly persistent — history of bloodletting and medicinal leeches.

From ancient Egyptian practices and the theory of balancing bodily humors to the 19th-century leech craze fueled by François Joseph Victor Broussais, leeches were once prescribed by the millions across Europe. Harvested in dangerous conditions and nearly driven to extinction, they eventually fell out of favor as modern science advanced.

But here’s the twist: leeches made a comeback.

Today, Hirudo medicinalis is FDA-regulated and used in reconstructive and plastic surgery to relieve venous congestion, thanks to its powerful anticoagulant properties.

Ancient theory. Modern application.
Sometimes medicine comes full circle. 🪱

📚 References

1. FibonacciMD. History of Leeches in Medicine. Published online. https://www.fibonaccimd.com/post/history-of-leeches-in-medicine. Accessed February 19, 2026.
2. Science History Institute. Medicinal Leeches and Where to Find Them. Science History Institute Stories & Perspectives. https://www.sciencehistory.org/stories/magazine/medicinal-leeches-and-where-to-find-them/. Accessed February 19, 2026.
3. National Geographic. Leech Blood Health Craze & Near Extinction. National Geographic Premium. https://www.nationalgeographic.com/premium/article/leech-blood-health-craze-extinct. Accessed February 19, 2026.
4. Ancient-Origins.net. Leech Collectors and the Perils of the Leech Trade. https://www.ancient-origins.net/weird-facts/leech-collectors-0019529. Accessed February 19, 2026.
5. Old Treasury Building. Leech Merchant. https://www.oldtreasurybuilding.org.au/lost-jobs/odd-jobs/leech-merchant/?srsltid=AfmBOoqZmmW7Nm2wfS1v0m8z85TmWchJF4GfK6g5gqf9QOHcVVhTeyXq. Accessed February 19, 2026.
6. Lethbridge News Now. Leech Collectors and the Leech Craze of the 1800s. https://lethbridgenewsnow.com/2017/11/24/leech-collectors-and-the-leech-craze-of-the-1800s/. Published November 24, 2017. Accessed February 19, 2026.