About Leeches

Contrary to popular belief, most leeches don’t rely solely on drinking blood. Some eat other, small invertebrates, and some feed off decomposing bodies.  Leeches that suck blood are called ‘Haemophagic’ leeches, ‘Haemo’ meaning blood, ‘Phago’ meaning to eat.  There are more than 600 species of leeches but only 15 of the species are used medicinally, so they are given a classification of their own – Hirudo Medicinalis or medicinal leeches.

How do Leeches drink blood?

  • The attach themselves to their hosts only until they become full, after which they will simply fall off and start digesting the blood they sucked out.
  • When they are sucking blood they release an anaesthetic, which is the reason why you don’t feel the leeches when they bite.
  • They then use suction and mucus to stay on their host.
  • Once they open up a bite wound they secrete an anti-clotting enzyme called Hirudin into the bloodstream so that blood will keep flowing.
  • Sometimes the blood will continue to seep for hours after the leech has been removed, which is due to the anti-clotting enzyme.


While all this may sound disturbing, being bitten by a leech isn’t deadly or dangerous, in fact, leeches are harmless.


The amount of blood loss isn’t really significant and when they’re full, which doesn’t take long, they simply fall off and go on with their lives.

Healing Qualities of Leeches


  • The European Medicinal Leech or Hirudo Medicinalis are used for microsurgery, grafting, and for constructive surgery.
  • Doctors use leeches for microsurgery because of their ability to remove blood that has coagulated. They relieve venous congestion and muscle flaps.
  • Leeches have anticoagulant, clot dissolving, anti-inflammatory, vasodilating, bacteriostatic and anesthetic effects that can be used to treat a variety of diseases and conditions.
  • Leeches are also known to treat black eyes.
  • Hirodin can be used to treat infections of the middle ear and is being tested as a systemic coagulant.
  • Leeches were popular during medieval times because they were known to cure infections, and remained a great option for treating infections until antibiotics were discovered.

Are Leeches Safe?

Leeches often cause disgust in people and they react with fear at the thought of using them for treatment.  But they have been used medicinally for centuries and they are not only relatively harmless but also very useful.


Pain from a leech bite is slight. Some people say they hardly notice it at all, a few people say it hurts as much as a wasp sting, but that level of pain is very rare.  A slight stinging usually lasts for only 1 to 5 minutes, after that the natural anesthetic kicks in.  Usually the patient’s pain is connected more to their level of anxiety than it is to leech bite, so the more relaxed or distracted the patient is, the less pain they are likely to feel.

Pruritis (Itchiness)

Itchiness on the site of the bite for a few days is a common side effect of leech therapy. It’s not an allergic reaction but it is advised that patients avoid scratching the area because that could delay healing.  Natural remedies for itching can be used, such as a cold moist wrap or vinegar wrap, and if the itching is intense antipruritic drugs like Fenistil ointment or oral antihistamine can be used.

Blood Loss

Blood loss from leeches is minimal. Leeches only suck about a teaspoon of blood and when they’re full they naturally fall off.



A leech’s body contains bacteria that may cause infection, but these micro-organisms are easily killed off with antibiotics, therefore it’s quite safe to use leech therapy.