The leech’s saliva contains anti-coagulant, anti-inflammatory, vasodilator, thrombolytic, antiseptic and anesthetic substances. All of these substances can also activate chronic illnesses or inflammatory processes. After the third or fourth session of treatment the state of the client’s health very frequently “worsens”, however this is a normal part of the NATURAL PROCESS. It does not cause any health problems or complications and is a part of HARMLESS SIDE EFFECTS.
We, hirudotherapists call this process “a positive response reaction of the body to the action of secretions of the leeches salivary glands”.
The state of health usually improves  after the fourth or fifth session of treatment. However often the acute local pain is 90% diminished after the first session!
By the leeches blood-letting, and the post-leeching discharge from a human body – microbes, toxins, blood clots and ballast substances are eliminated, and the organism is cleared in the NATURAL WAY. In addition it promotes the improvement of the one’s blood circulation, and – the most importantly – it leads to the normalization and improvement of micro- circulation on a way to homeostasis!. This type of action CANNOT BE achieved using chemicals and pharmaceutical drugs.

When restoring blood circulation by delivering the oxygen into the veins and arteries, connections are restored between the separate organs and the proper activation of local and general immune reactions can proceed. Because of the difference in osmotic pressure due to the leech secretions, body’s fluids start to move from internal organs to the surface of the skin. Thus, the property of the leech bite wound do continue bleeding, encourages the movement of even previously immobile fluids (chronic inflammation, damaged connective tissue, etc.) for the extended discharge after the leech has been detached. There is nothing to be afraid about – it is a part of the  NATURAL PROCESS. On the other hand, only slight and/or short bleeding after the first few sessions indicates impaired blood circulation and poor immunity. To restore this insufficiency the medicinal leeches should be applied to the same area (not the same points!) shortly – usually within 7 days.