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What Are the Pros and Cons of Leeching?

By C. K. Lanz
Updated Feb 25, 2024
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Leeching is a beneficial medicinal treatment increasingly used in microsurgery and reconstructive surgery to reduce blood coagulation, relieve pressure form pooling blood, and stimulate blood circulation in reattachment operations. Potential drawbacks include excessive bleeding, allergic reactions, and a slight risk of infection. Medicinal leech therapy has a long history dating back to ancient Greek and medieval medicine. A resurgence in the use of medicinal leeches began in the 1980s, when scientific evidence emerged supporting the use of this therapy for microvascular surgery.

This practice has a long history in medicine. Leeching was used by Nicander, a Greek physician who practiced in 200 BC. Throughout medieval and early modern history, leeching was commonly used to balance the humors by removing blood from patients believed to be out of balance or sanguine. Many other diseases were also routinely treated by leeching.

Starting in the 1980s, the use of leeching became increasingly common as a therapy for microsurgery as well as microvascular and reconstructive surgery. After these types of surgeries, venous blood may have difficulty leaving the affected area because of damaged veins, and oxygen-rich blood cannot enter. As a result, the skin turns purple or blue and feels cold. Leeches attach to these discolored and cold areas.

Leeches stimulate blood circulation by releasing a blood thinner in their saliva that keeps blood flowing from their bite for up to two days afterward. This is therapeutic because the venous blood is removed, allowing fresh blood to enter the affected area and keep it healthy and healing. In other words, leeches help keep a patient’s fresh blood flowing to the discolored area while the affected veins have time to heal.

Patients typically undergo this therapy in a warm room because warm temperatures combined with certain body positions help blood flow. A nurse usually attaches several leeches to the affected area, a process that can take time if the leeches are uncooperative. In some cases, a drop of sugar water or a needle poke to draw a little blood is necessary to entice the leech to attach where it should.

When a leech attaches, it released a mild anesthetic in its saliva, so the bite should not hurt. They typically feed for at least 15 minutes and can sometimes suck for an hour. One leech will remove only between 1 and 2 teaspoons of blood. The fact that blood will continue to flow for up to two days after treatment ensures that the venous blood is removed. Medicinal leeches are never reused.

Medicinal leeches used in leeching are similar in appearance to fat, black worms and are usually the species Hirudo medicinalis. They are spineless, live in water, and range in size from 0.5 to 2 inches (1.27 to 5.08 centimeters). These leeches are grown and maintained in a sterile environment in a hospital or clinic to reduce the risk of infection. Despite the small chance of being infected by a medicinal leech, some patients may be given a preventative antibiotic during leeching.

Allergic reactions and excessive bleeding are other potential drawbacks to using medicinal leeches. Although it is normal and therapeutic for blood to continue to ooze from the bite for one to two days after treatment, in some cases bleeding can become excessive. If a patient’s blood count gets too low, a blood transfusion may be required.

Allergic responses to leeches have also been reported. Itching and rash are common signs, although anaphylaxis is also possible. Some patients may experience minimal scarring at the bite site. In light of these potential complications, hemophiliacs and patients who are immunocompromised or taking a drug or vitamin that increases the risk of excessive bleeding should be cautious about undergoing leeching.

Once a leech has finished feeding and falls off, there are three legal ways to dispose of it depending on the country. The leech can be returned to a retirement pool, or it can be killed by freezing or immersion in alcohol. Common practice in the United States is to kill the used medicinal leech. Dead medicinal leeches are potentially infectious and should be treated like hazardous waste material. Releasing live medicinal leeches into the wild is a potential violation of drug, environmental protection, and hazardous waste laws.

Patients may be hesitant or squeamish about leeching due to the nature of the treatment. This unease is often abated once the patient is educated about leeches and the procedure. For most patients, leeching is a noninvasive and painless way to stimulate blood circulation after certain types of surgeries.

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Discussion Comments
By browncoat — On Aug 22, 2014

@Fa5t3r - I do have to wonder how efficient it is to keep leeches though, as you'd have to sterilize them completely to ensure they weren't going to infect a wound, and you'd have to breed them and keep them healthy and ready for treatments. That can't be cheap, particularly compared with more traditional treatments.

By Fa5t3r — On Aug 21, 2014

@Iluviaporos - Actually, there was some medical basis for blood letting, although it was not understand and often misused. It would help the body fight certain infections and could aid in reducing a fever. It doesn't have any modern applications in that sense though, as there are many other options that work better now.

Leeches are actually incredibly useful for certain tasks and it's a shame that they are so misunderstood by the general public. They are ideal for removing blood from bruise sites, for example, which speeds healing a great deal. And, as it says in the article, they are wonderful in microsurgery as well, particularly in cases like surgery on the fingers, where losing the blood supply could quickly lead to serious problems.

By lluviaporos — On Aug 20, 2014

I imagine one of the biggest cons is convincing a patient to allow the doctor to use leeches in the first place. Stress is a major factor in the healing process, and if someone is completely freaked out by the idea of having little blood-suckers attached to their wound, they are going to be feeling a lot of stress.

Not to mention the fact that leeches are strongly associated with quack medicine, due to the fact that they used to be used for blood letting, which was once considered an answer to everything (in spite of the fact that it would obviously make people weaker, not stronger).

Overcoming these associations would be very difficult, even in a modern medical setting.

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