The medical use of leeches is anything but new – it goes back thousands of years, all the way to ancient Egypt. Leechse (latin name Hirudo medicinalis) were already depicted in wall paintings over 3,000 years ago. Ancient texts from India, China, Persia, and Greece also describe their use. Famous physicians like Galen and Avicenna recommended leeches for treating a variety of illnesses.
In the European middle ages, leeches were part of every traveling barber’s or healer’s toolkit. The red-and-white striped barber-pole pole still reminds us of the bloodletting tradition, in which leeches were seen as a gentler option. In the 19th century, leech therapy became so popular that France alone used up to 100 million leeches a year. Demand was so high that natural populations declined, and leeches had to be imported from far-off regions, including Asia. Around the 1920s, the discovery of hirudin – a natural anticoagulant in leech saliva – and the use of leeches in reconstructive surgery led to a brief comeback. But after World War II, the method faded from hospitals, partly because synthetic alternatives for anticoagolation like heparin became available.
As modern medicine increasingly focused on scientific evidence, leech therapy was pushed aside. After all, it was originally based on the humor theory – a concept long outdated by today’s knwoledege. But by the late 20th century, leeches made a quiet return, especially in microsurgery. Today, they are used to treat venous congestion after transplants, among other things.
What We Know Today
Today’s understanding of leech therapy focuses less on tradition and more on biochemistry. The saliva of medical leeches contains a whole cocktail of active substances – including hirudin, bdellins, eglin C, calin, and hyaluronidase – which have been shown in lab studies to reduce inflammation, inhibit clotting, ease swelling, and loosen tissue.¹ ²
Despite many historical accounts and a growing list of identified compounds in leech saliva, clinical research remains somewhat limited – aside from case reports in plastic surgery:
- A recent study looked closely at the effects of Hirudo verbana saliva.¹ It found anti-inflammatory properties, the ability to neutralize harmful oxygen molecules, and even targeted effects on cancer cells.
- A 2024 review also summed up 12 high-quality clinical trials.² It showed that leech therapy may help reduce symptoms in conditions like osteoarthritis, back pain, and circulation problems.
The current results are encouraging. But more research – and proper funding – is needed to build strong scientific evidence and to confirm the positive effects many practitioners have observed in everyday use.
Conclusion
With the identification of key active substances in leech saliva and the positive results from recent studies, the potential of leech therapy is evident, though further research is needed.
If you would like to learn more about the possibilities of leech therapy for your animal, I would be happy to offer a consultation!
References
- Michalsen A, Roth M. Blutegeltherapie. Vol 3. Karl F. Haug Verlag; 2012.
- Whitaker IS, Rao J, Izadi D, Butler PE. Hirudo medicinalis: Ancient origins of, and trends in the use of medicinal leeches throughout history. Br J Oral Maxillofac Surg. 2004;42(2):133–137. doi:10.1016/S0266-4356(03)00242-0
- Bilden A, Sabancılar İ, Yalçın Azarkan S, et al. Investigating the Therapeutic Potential of Crude Leech Saliva Based on Its Anticancer, Antioxidant, and Anti-Inflammatory Effects. Curr Issues Mol Biol. 2025;47(5):328. doi:10.3390/cimb47050328
- Hosseini M, Jadidi A, Derakhshan Barjoei MM, Salehi M. Applications of leech therapy in medicine: a systematic review. Front Med (Lausanne). 2024;11. doi:10.3389/fmed.2024.1417041
Pic: Sandra Göttisheim
