Although leeches are no longer the norm for treatment, a report published in the Annals of Internal Medicine (November 4, 2003) showed evidence that leeches may reduce pain and stiffness in patients with arthritis of the knee. German researchers maintained that leech saliva contains anti-inflammatory substances and other chemicals, which could relieve arthritis symptoms. During the study, the researchers compared a single treatment with 4 to 6 leeches with that of a 28-day regimen of topical diclofenac.
Leeches were put on painful joints of the affected knee of 24 patients and left on for ~70 minutes, until the leeches detached themselves. After 7 days, patients in the leech group reported significantly less pain, compared with those in the diclofenac group. Additionally, benefits in function, stiffness, and overall arthritis symptoms were maintained through 91 days of follow-up, the report said.