Hear the word “leech” and comical stereotypes may come to mind: a slimy person known for sucking funds dry or a clingy friend you can’t shake. But leeches may have the last laugh. The bloodsucking worms are showing promise in providing relief from the pain of osteoarthritis (OA), after several years of being used successfully during microsurgery to both numb skin and keep blood from clotting. They’ve even been approved by the Food and Drug Administration (FDA) as a medical device.

When leeches bite into skin, they release a substance through their saliva that keeps blood flowing until they are full. Researchers know that some pain-relieving substances exist in leech saliva, too, based on the success of using leeches on people in pain. Although the practice is not widespread and may be looked at skeptically, studies have been positive and are continuing.    

German researchers conducted a randomized, controlled trial of leeches in 51 people with knee OA. They compared one application of four to six leeches, placed around the knee, with a 28-day topical treatment of diclofenac, a nonsteroidal anti-inflammatory drug. Those who had the leech treatment had less pain on the seventh day – and improved in tests of function, stiffness and overall arthritis symptoms during a 91-day follow-up – than those who received topical treatment. Pain decreased by two-thirds in the leech group, compared with only one-fifth in the diclofenac group.  

Next the researchers, led by Andreas Michalsen, MD, deputy medical director at the University of Duisburg-Essen in Germany, conducted a randomized trial on degenerative thumb joints. A group of 32 participants was divided into groups of 16. One group applied diclofenac ointment twice a day for 30 days; the others were treated once daily by having up to three leeches attached to the base of their thumbs. The leech group showed increasingly greater improvement over the diclofenac group. Two months after the therapy, the leech group reported significantly less pain and their hand and arm disability had decreased by 47 percent compared to 2 percent for the ointment group.

“Leech therapy effectively reduced pain and improved joint function after three to seven days and lasted at least two months,” says Dr. Michalsen.

The Continuum Center for Health and Healing in New York, part of Beth Israel Medical Center, uses leeches to treat people with knee OA. Each leech therapy visit takes about three hours – including one hour in which the leeches are latched onto body and two follow-up exams – and costs $600. Insurance does not cover the treatment, but the non-profit Biotherapeutics Education and Research Foundation (www.bterfoundation.org) might.