For most of us, leeches conjure up feelings of fear and revulsion. The idea of one of these strange creatures attaching itself to you in order to drink your blood is probably quite disturbing. This is a normal reaction. I used to feel the same way. That said, leeches are one of the oldest medicinal products in the world. These tiny but effective animals should not be underestimated.
My first encounter with leeches was in March 1992. It left a deep impression on me. I had just transferred from the cardiology department at Berlin’s Humboldt Hospital to the department for naturopathy at what was then the Moabit Hospital. That’s where I was supposed to admit a new patient, a woman in her mid-sixties. She suffered from such severe osteoarthritis of the knees that she was barely able to climb stairs, and could get into a car only with great difficulty. The attending physician ordered leech therapy for the next day.
I was surprised. I had heard that leeches were used in some areas of naturopathy — usually by alternative practitioners — but at a renowned hospital? When the appointed time for the leech therapy arrived, I met the nurse who was already on her way to the patient with a pot full of the little animals. Cheerfully, she asked whether I wanted to apply the leeches. (For osteoarthritis of the knees, four to six leeches are placed around the joint.) I couldn’t bring myself to touch the leeches. To be honest, I was nervous that they would bite me.
Over the next few days, I was astonished to see that the patient, who was much braver than I, was doing fantastically well. But how could that be? How could such a seemingly unscientific, medieval procedure make pain in the knees disappear?
As I learned, a leech’s saliva contains numerous compounds that prevent the host from suffering any harm. One of these substances is hirudin, a polypeptide (protein) that is very effective at stopping blood from coagulating — thus prolonging the time during which the leech can consume its food. In one study, scientists at Switzerland’s University of Lausanne were able to show that hirudin is not only the strongest known anticoagulant, but also that it notably reduces inflammation of the joints. Leech saliva also contains hyaluronidase, an enzyme that helps different pharmacologically active substances permeate deeper into the tissue, including the joint capsule of the knee. Swelling at the joints is likely reduced after a treatment with leeches because the lymph is activated from the small local venesection that takes place. Moreover, the bite and suction from the leeches themselves cause neural stimuli that change the perception of pain and “overwrite” it in the brain, so to say — a method of pain management that acupuncture also utilizes.
How exactly is leech therapy carried out? First, the site that is to be treated should be cleaned with water — and only water — since leeches don’t like aromatic substances and disinfectants and won’t bite if those are applied. The leech is then positioned gently on the area. To prevent it from wandering from the treatment area, a small shot glass or cupping glass can be placed over it. Once the leech has bitten, it’s left undisturbed until it detaches by itself, usually after 20 to 60 minutes. Once a leech has bitten, a wound in the shape of the star in the Mercedes logo remains due to the typical formation of the three jaws. The wound takes a few weeks to heal, yet it barely hurts, because leeches release numerous locally numbing and pain-relieving substances into the wound when they bite — after all, the leech doesn’t want to be found by its host too soon. For hygienic reasons, leeches can only be attached to a human once — they can live off one meal for up to two years.
Leech therapy can be repeated — at an interval of four to six weeks, or when the effect has worn off — and is an effective long-term treatment method for treating arthrosis. But if a patient doesn’t respond after three treatment attempts, success is unlikely. In practice, treating the affected joints in patients with arthrosis at least twice a year has proven successful.
I witnessed many successes in treating osteoarthritis of the knees with leeches during my time at the Moabit Hospital in the ’90s. Many years later, when I was at the Department for Internal and Integrative Medicine at the University Hospital in Essen, Germany, I got the opportunity to do research on medicinal leeches. In two small studies, my team found that leech therapy was more effective for osteoarthritis patients than physical therapy or the anti-inflammatory cream Diclofenac. Not only did pain decrease, but we were also able to demonstrate continued improvement of knee joint function, and, as a result of these two things, an improvement of the patients’ quality of life.
A short while later, another team of researchers at the University Hospital in Aachen, Germany, conducted an even bigger study on leech therapy in osteoarthritis of the knees. In order to determine the placebo effect precisely, this study was single-blinded. This meant that one group actually received leeches as treatment, the other group received a minuscule cut in the skin and a thick bandage, with a “dressing screen” concealing what was actually going on. The patients in question would not be able to tell who got what, neither from the pain nor the puncture site. Not only did the study demonstrate that leech therapy had a strong effect, it also showed that the benefits go beyond the placebo effect: The group that received the leeches did notably better than the other group.
Despite the scientific evidence available, the prejudices against this “archaic” therapy are hard to overcome.
On average, 80% of leech therapy patients experience a pain reduction of more than half (60% on average), three days after a one-time therapy with four to six leeches on the knee. In more than two-thirds of patients, this effect persists for more than three months. Almost half the patients (45%) use less pain medication after 10 months. Ultimately this means that the effect leeches have — and this should be said quite plainly here — exceeds the effectiveness of all traditional pain-relieving therapies for osteoarthritis of the knees known today by far. In many cases, pain medication can even be discontinued, and side effects can thus be reduced.
There have been other medical successes with leeches: We conducted a study on their effectiveness in the treatment of rhizarthrosis — arthrosis of the thumb joint. This ailment affects many people, especially women over the age of 50. The treatment options are quite limited; usually surgery to preserve function of the joint is required sooner or later. Here, leeches showed a clear superiority to the Diclofenac control group. We were able to publish the results in the renowned journal Pain.
Subsequently, we were also able to demonstrate the effectiveness of leech therapy in the treatment of tennis elbow (epicondylitis), a very painful tendinitis that can occur as a result of chronic excessive strain after sporting activities but that can also be occupational. In 2016, when I was working at the Immanuel Hospital in Berlin, my group and I conducted a study on leech therapy in the treatment of chronic lower back pain: The results were published in 2018 in the journal of the German Medical Association (Deutsches Äerzteblatt), and again leech therapy showed a considerable advantage over conventional therapeutic exercise in this common ailment.
But where does leech therapy go from here? The findings of all studies on osteoarthritis of the knees have been summarized in a metanalysis by Gustav Dobos and his team in Essen; in light of this data, which shows the benefits of using leeches, medical insurance companies should be inclined to cover the funding of this therapy. In the overall evaluation, leeches have proven to be the best possible pain-relieving therapy for painful arthroses — better than antirheumatics, pain medication, or certain surgeries.
But despite the evidence available, the prejudices against this “archaic” therapy are hard to overcome. That’s why many of my patients are still forced to pay for the treatment out of their own pocket, while the costs of orthopedic injections, arthroscopies, and other technical intervention — by no means more effective — are covered. I hope that we can eventually overcome our biases against leeches, so that more of us can take advantage of their incredible healing power.