Leech therapy, a practice with roots stretching back more than 2000 years, has been scientifically validated in modern medicine and is now well established in plastic and reconstructive surgery. It may also offer benefit in conditions such as osteoarthritis, venous disorders, and chronic pain. Recently revisited within integrative and traditional medical systems, leech use has had a dramatic history — once widely promoted as a cure-all, then pushed out of favor during the cholera epidemics.

What Are Leeches?

Leeches of the subclass Hirudinea are annelids comprising approximately 290 species that inhabit freshwater environments, and more rarely saltwater or moist terrestrial habitats; among them, Hirudo medicinalis is used for therapeutic purposes.

As parasites, leeches can attach to sites such as the nasopharyngeal cavity, bronchi, and esophagus, often after exposure to contaminated surface water. As they enlarge, they can cause increasing discomfort and, when they involve the respiratory tract, may become life-threatening. Clinical presentation can include nasal or oral bleeding. Removal is typically performed endoscopically, with care taken not to sever the leech because of the risk for severe bleeding.

Unlike many other worms, leeches have little to no ability to regenerate if severed. They are hermaphroditic and reproduce sexually. Their bodies are divided into anterior and posterior ends, each with a sucker, and include segmented preclitellar and clitellar regions separated by the mesocoel. Of particular note is their symbiotic relationship with the gram-negative bacterium Pseudomonas hirudinis, which helps preserve and digest the blood the leech ingests within the cells of its intestinal pouches.

Historical Background

More than 2000 years ago, physicians began using leeches as part of bloodletting therapy, a practice that endured for centuries. During the Middle Ages, leech use spread into Europe through translations of medical texts from ancient Greece and the early Islamic world. Well into the 19th century, European physicians continued to rely on these teachings, using leeches to help restore balance among the four bodily humors, in keeping with the humoral theories then dominant in medicine. Leeches were used broadly to treat a wide range of illnesses and were also employed for general prevention.

From the late 18th to 19th century, as new disease theories gained traction, leech therapy became a widespread medical trend in Europe and North America and was extended to treat nearly every type of ailment. The practice fueled the collection, trade, and use of millions of leeches each year, with applications sometimes placed in unexpected sites including the inside of the nostrils, the lower lip, the chest, or on the sides of the body.

William Buchan’s Domestic Medicine also underscored the difficult and often uncertain nature of leech therapy. In the first edition, published in 1769, Buchan was firmly opposed to the use of leeches, which at that time played only a minor role in medical practice. But by the 19th century, evolving medical theories, changes in the market, developments in aquaculture, and the growth of the international pharmaceutical trade had shifted attitudes toward leech use.

François-Joseph-Victor Broussais, the French physician and director of the Val-de-Grâce Military Hospital in Paris, supported this all-purpose approach through his theory that disease arose from inflammation caused by disruptions in normal physiologic processes, which he believed underlay all illness. He treated soldiers with typhus, dysentery, and enteritis in the same manner, and newly admitted patients were routinely prescribed 30 leeches.

Using leeches on the wounded and critically ill was considered a novel approach. Broussais’s followers viewed them as a gentler alternative to traditional bloodletting, believing they helped relax the body’s nervous energy. The method also made it possible to treat hard-to-reach areas such as the ear canal, nose, and mouth. His model of health and disease was easy for the public to understand, fit with long-held beliefs about bloodletting, and offered a treatment approach that felt accessible.

Broussais’s sustained demand for leeches gave rise to a lucrative, transnational trade that provided income for collectors, breeders, merchants, pharmacists, quacks, and peddlers. They even found their way into the fashion and culture of the time, inspiring poems, embroidery patterns, and leech vials used by pharmacists and the wealthy.

However, due to dwindling wetlands, overharvesting, and a shortage of collectors, the procurement of these small creatures was likely quite the opposite. At its peak, even the import of 33 million leeches annually into France could no longer meet the demand. By the end of the 18th century, medicinal leeches had been nearly wiped out in Ireland, England, Wales, and the Netherlands, so leech farming was ramped up, or, out of necessity, leeches were imported from Russia, Hungary, and the Ottoman Empire.

However, large-scale leech breeding also introduced new challenges, including disease, reproductive difficulties related to oxygen deprivation in overcrowded marshy fields or satiation periods that could last up to 6 months, and pressure from predators. Efforts to improve the care of live leeches included adding iron to the water, changing the water regularly, and recreating their natural habitat. Used leeches were often returned by practitioners to nearby bodies of water, a practice that may have helped save the species from extinction. Today, leeches are protected by law in Germany and several other European countries.

In response to these challenges, French physician Jean-Baptiste Sarlandière was among the first to develop a mechanical device in 1817 that used pumps, valves, and puncture needles to provide a gentler and more controllable form of bloodletting. Several decades later, Charles Louis Heurteloup refined the design into a more practical two-part cylindrical device with a round lancet and suction pump. Compared with leeches, the device offered several advantages, including easier storage, greater portability, and higher capacity.

Following the unsuccessful use of leeches — which Broussais had excessively touted — during the cholera epidemic of the 1830s, this form of treatment declined in popularity, so that by the end of the 19th century, most European physicians had abandoned it. In North America, their use persisted well into the 20th century due to their natural abundance, mostly for emergencies or to treat a swollen, black eye. They remain a part of Arabic, Ayurvedic, and East Asian folk medicine, as well as the resurgent field of Traditional European Medicine.

Rise in Reconstructive and Plastic Surgery

In 1985, an impressive case of the second successful ear replantation caused a sensation. The American plastic surgeon Joseph Upton was able to save the reimplanted ear of a 5-year-old boy using leeches after it had threatened to fail postoperatively. Leeches also offer an alternative to surgical revision in cases of venous stasis following finger replantation, although proximal stasis or late application was unfavorable (44% of fingers survived overall in a small case study compared to 36.2% in replantation cases).

Their use in cases of venous flap stasis following pedicled distant flap surgery in the head and neck region is also worth attempting. In 2004, the US Food and Drug Administration approved the use of medical leeches in reconstructive and plastic surgery.

This story was translated from Univadis Germany, part of the Medscape Professional Network.