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Why you should love a leech: bloodletting’s modern revival
Once considered a symbol of old-fashioned quackery, the leech is having the ultimate medical comeback.
Once considered a symbol of old-fashioned quackery, the leech is having the ultimate medical comeback. Far from being just a footnote in the dusty pages of ancient remedies, this slippery creature has slithered its way back into modern surgical theatres—saving fingers, ears, noses and, sometimes, lives.
A gruesome past with a purpose
The use of leeches in medicine dates back over 3,000 years, appearing in Egyptian tomb paintings, ancient Indian texts, and Greek and Roman medicine. In these early traditions, disease was often thought to arise from an imbalance in the body’s four humours: blood, phlegm, black bile, and yellow bile. Too much of one, and illness followed. The solution? Let out some blood.
By the 19th century, Europe had entered full-blown “leech mania.” Millions of leeches were harvested each year to drain excess blood and restore balance. Bloodletting—whether by blade or by leech—was a mainstay of medical treatment. In fact, the familiar red-and-white barber’s pole originated from this practice. The pole symbolised the stick patients would grip during bloodletting, the red stripes stood for blood, the white for bandages—and the round glass top represented the globular leech jar once commonly perched on the counter of every barber-surgeon.
But as medical science evolved, the leech lost its lustre. By the early 20th century, it had faded into obscurity—dismissed as outdated, unnecessary, even medieval. That is, until modern surgery gave it a second chance.
How do leeches help today?
Today, we know the value of leeches lies not in how much blood they take, but in what they leave behind: a precise bite that helps restore blood flow to congested tissues, especially after reconstructive surgery. A single leech can consume up to 10 millilitres of blood—almost 10 times its body weight—but more importantly, it injects a chemical cocktail through its saliva, including:
- Hirudin, a powerful anticoagulant that prevents clots
- Calin, which keeps the blood flowing after the leech drops off
- Anaesthetics that numb the bite
- Anti-inflammatory and antimicrobial agents that reduce swelling and infection risk
This biochemical arsenal is what makes leeches a valuable, if slightly off-putting, addition to modern microsurgery—especially for reattaching delicate parts like fingers or ears.
From quack to clinical: the science of hirudotherapy
Modern leech therapy, or hirudotherapy, began gaining traction in the 1960s and was formally recognised by the U.S. FDA in 2004. Today, leeches are officially categorised as living medical devices.
At hospitals across Aotearoa New Zealand and Australia, like St Vincent’s in Melbourne and Middlemore Hospital in Auckland, leeches bred under strict biosecure conditions are deployed in operating rooms when venous congestion threatens the survival of reattached or reconstructed tissue. Surgeons place leeches directly onto the affected area. Once they latch on, their work begins—draining pooled blood and keeping vessels open just long enough for new circulation to take hold.
At Middlemore Hospital in Auckland, leeches are still used. The most common use is for a replant where the veins are inadequate.
At hospitals across Aotearoa New Zealand and Australia, like St Vincent’s in Melbourne and Middlemore Hospital in Auckland, leeches bred under strict biosecure conditions are deployed in operating rooms when venous congestion threatens the survival of reattached or reconstructed tissue.