Nature Champions: Medicinal Leech

Image of a medicinal leech resting in a shallow pool of water.
Roger Key

The elusive Medicinal Leech Hirudo medicinalis, the UK’s largest leech, is an iconic freshwater animal with striking vivid orange and yellow markings. They are found in ponds and ditches, where they commonly feed on frogs and provide an important part of the food web. The Medicinal Leech is also entangled in British medical history, as during medieval times they were common, and often used as a medicinal cure. Even today, leeches are essential for medicine and are still used to increase blood circulation.

Action Needed

  • Support a captive breeding programme for Medicinal leech.
  • Support the Species on the Edge project and reintroductions of this species at historical sites. 
  • Ensure the Scottish Biodiversity Strategy is fully implemented.


The medicinal leech is rare throughout its range in Europe and extinct in much of its former range. This is due primarily to the overharvesting of leeches in the past century for medicinal use. The proportion of each population that are of breeding size is often quite low and removal of large leeches for medicinal use may have had a disproportionate effect. Such exploitation is now illegal in the UK as the medicinal leech is listed in Schedule 5 of the Wildlife & Countryside Act. 

The main threats now to this species in the UK come from habitat change, especially poor water quality, and from the loss of farm ponds and the deepening of small lochs for fish. 


MSP Nature Champion

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