Leech therapy is not new as they seem to have come to the aid of humans more than 3000 years ago.

There are many studies which look into the medicinal purposes of leeches. A recent study also showed that a single session of leeching helped markedly cut down arthritic knee pain.
Researchers from the University of Duisburg-Essen in Germany have said that the improvement levels could be compared to the relief achieved from a daily moderate dose of painkillers like ibuprofen.
Leeches’ saliva is thought to contain a large number of analgesic, anaesthetic, and blood-thinning compounds which can effectively battle pain and inflammation. The maximum benefit of hirudotherapy can be achieved with three sessions, with a gap of a week between each session to achieve the best results. According to experts, the secretions from leeches’ saliva can be used to treat blood-clotting, inflammation, pain and disease
Source-Medindia