Hirudotherapy (leech therapy) is a medical treatment that uses leeches (Hirudo medicinalis) to remove pooled or clotted blood for medical purposes.

Leeches are freshwater worms that suck blood. They secrete a natural blood thinner that helps keep the blood flowing and improves survival of wounded tissue.

Hirudotherapy is approved by the US FDA for healing skin grafts. Hirudotherapy is also used for osteoarthritis, leg sores caused by poor circulation, and other conditions, but there is no good scientific evidence to support most of these other uses.

Companies that raised and marketed leeches before 1976 in the US are permitted to continue doing so. But those marketing leeches after 1976 are required to get FDA approval.
When applied to the skin: Hirudotherapy is likely safe when used appropriately by a medical professional. It is an FDA-approved medical therapy. Hirudotherapy is usually well-tolerated. Side effects might include itching, redness, swelling, and bleeding.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if hirudotherapy is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.


NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
  • Skin grafts. Hirudotherapy is approved by the US FDA as a medical therapy for healing skin grafts.
Possibly effective Effectiveness definitions
  • Osteoarthritis. Hirudotherapy seems to help reduce pain in people with osteoarthritis, especially in people with osteoarthritis of the knee.
There is interest in using hirudotherapy for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
Insufficient evidence Effectiveness definitions

Dosing & administration

Leeches used for hirudotherapy should only be applied by a qualified healthcare professional. The therapy usually involves applying 1-6 leeches to the skin and leaving them on the skin until they fall off. This often occurs after about 40 minutes. A gel made from leech saliva has also been applied to the skin for conditions involving pain. Be sure to seek and follow relevant directions from your physician or other healthcare professional before using this therapy.

Interactions with pharmaceuticals

It is not known if this treatment interacts with any medicines. Before using this treatment, talk with your health professional if you take any medications.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods.
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This monograph was last reviewed on 26/08/2023 10:00:00 and last updated on 01/05/2022 09:39:52. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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