The medically beneficial aspect of leeches, which may initially seem surprising, was actually a clever move made by leeches long ago. Being beneficial to the host mammals is, one can assume, vastly preferable to harming them. To put it in somewhat simplified ecological terms, this is a good example of successful, mutually sustainable utilisation, of a balanced give-and-take relationship. Science and the pharmaceutical industry have long been aware of the fact that, with leech saliva, evolution has brought forth a complex and wonderful mixture of active ingredients which are able to ingeniously interact with the complicated blood coagulation cascade.  As blood is connected with all diseases in some way or other, the leech, with its natural method of bloodletting involving many active ingredients, covers a wide range of indications. 

Leech applications include use in: 

  • rheumatism
  • herpes zoster (shingles)
  • varicosis
  • tinnitus
  • thrombosis
  • furuncles and carbuncles
  • sinus infections
  • tonsillar abscess
  • adnexitis, parametritis
  • mammary gland inflammation
  • gall bladder inflammation
  • venous congestion of
    skin and tissue grafts in
    reconstructive surgery
  • orchitis
  • phlebitis
  • arthrosis
  • arthritis
  • ulcus cruris
  • tendinitis,
    (tennis elbow,
    golf arm)
  • hypertonia
  • apoplexy
  • angina pectoris
  • thrombophlebitis 

This list is not intended to be comprehensive; it is only meant to give an impression of the broad spectrum of possible leech therapy applications. 

What exactly do leeches do to us?



 To begin with, let us make one thing clear: the bite of the leech is not painful. This is quite reasonable if one considers that a leech in the wild would not at all be interested in being noticed. Whether or not there exists an anaesthetic in the saliva which serves to relieve pain, remains controversial. The actual bite has been variously described as being similar to the sting of a nettle, a mosquito bite, a slight, dragging pain, the prick of an injection needle – or even as being completely painless. Histamine-like substances may subsequently cause a slight itch, similar to that of a mosquito bite. The leech’s method of biting is responsible for its being nearly painless.  Three radiating jaws, each equipped with about 80 tiny sharp teeth carefully work their way into the skin in order to reach their desired goal: blood. As shown in the figure, there are tiny gaps between its miniscule teeth through which saliva is secreted. With this application technique, the leech works as an extremely precise medicinal product injecting the active ingredients exactly into the target area.

Active Substances

 The SALIVA contains the following thus far identified ingredients: 
HIRUDIN (the name is derived from Hirudo medicinalis = medicinal leech):  inhibits blood coagulation. During the sucking procedure, which lasts about 30 minutes, it is of course necessary to keep the wound open and the blood flowing. 
CALIN: also inhibits blood coagulation.  Subsequent to the quick effects of hirudin, calin purifies the wound by means of secondary bleeding, a process which takes about 12 hours.  The familiar gentle bloodletting has begun.
While this is going on, HYALURONIDASE, the diffusing substance, goes into action, paving the way for the bioactive (and healing) substances. It is still controversial as to whether hyaluronidase has antibiotic properties.
One probably histamine-like substance (perhaps acetylcholine) causes vascular dilatation: blood flows towards the site of the bite.
EGLINs, BDELLIN, APYRASE, and COLLAGENASE contribute to inhibiting blood clotting in various ways. Moreover, several of these substances have anti-inflammatory and other properties.
Additionally, DESTABILASE, PIYAVIT, and other substances round off the natural composition of ingredients.