Bloodletting — the practice of withdrawing blood from a person’s veins for therapeutic reasons — was common for thousands of years. In this Curiosities of Medical History feature, we look at the history of bloodletting and how it eventually fell out of favor with the medical community.

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Image credit: National Library of Medicine

Also known as phlebotomy — from the Greek words phlebos, meaning “vein,” and temnein, meaning “to cut” — bloodletting is a therapeutic practice that started in antiquity.

Today, however, the term phlebotomy refers to the drawing of blood for transfusions or blood tests.

Some sources suggest that the original practice of bloodletting is more than 3,000 years old and that the Ancient Egyptians, Greeks, and Romans — as well as many other ancient peoples — all used it for medical treatment.

But what is the origin of the notion of bleeding someone to help them get better?

Hippocrates — an Ancient Greek physician who lived in the fifth century before the common era and was one of the most important figures in the history of medicine — practiced medicine according to the theory of the four humors, or “humoral theory.”

This theory posited that there were four key humors, or liquids, in the human body and that imbalances in these humors were responsible for many physical and mental illnesses.

According to the most influential version of this theory, these humors were: black bile, yellow bile, phlegm, and blood.

In the second century before the common era, Galen — a famous Roman physician who also subscribed to the humoral theory — promoted arteriotomy, a bloodletting method, as a means of reestablishing the balance of the four humors and treating a variety of symptoms.

According to Galen, a bloodletting incision into the veins behind the ears could treat vertigo and headaches, and letting blood flow out through an incision in the temporal arteries — the veins found on the temples — could treat eye conditions.

The principle behind bloodletting is to remove some blood in a controlled way so that the patient does not end up bleeding profusely.

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However, as some of Galen’s contemporaries observed, the famed physician could sometimes get carried away when administering this treatment.

Prof. Susan Mattern — a historian based at the University of Georgia in Athens — emphasizes one such account in a paper in The Lancet:

“[Galen] was an adamant defender of bloodletting against those who doubted its efficacy. Galen’s methods could be very messy: he let so much blood from one patient that the other doctors in attendance joked about it, comparing the sick man to a butchered animal: ‘Man, you have slaughtered the fever.'”

Bloodletting continued to play a role in medicine throughout Medieval Europe, and it persisted as a common therapeutic method up until the 19th century, when it gradually started to fall out of fashion.

The instruments that physicians commonly used for bloodletting ranged from grotesque-looking scalpels to tools and methods that some alternative medicine practitioners still use today. They included:

  • fleams, which looked somewhat like Swiss knives, producing several kinds of blades
  • spring lancets with a single thin blade
  • terrifyingly named “sacrificators,” which had multiple blades
  • cups that the physician could place over the incision to collect the blood
  • leeches, which some people still use for therapeutic reasons today

Bloodletting was particularly popular in the Middle Ages, when doctors would use it not just to treat illness but also to prevent it.

In the book, Medieval Bodies: Life, Death and Art in the Middle Ages, Dr. Jack Hartnell — who is a lecturer in art history at the University of East Anglia in Norwich, United Kingdom — describes some of the uses of bloodletting, as well as some of the ways in which physicians carried out this procedure.

Dr. Hartnell writes that according to medieval medical practice:

“Purging the wet and warm humor that was the blood both cooled and ventilated the patient’s core and was used as a prophylactic insurance against illness to come: It could prepare the body for predicted future biological shifts or seasonal changes that might push it into misalignment — anything from forthcoming menstruation to the onset of a particularly hot summer.”

As for applying bloodletting as a treatment, Dr. Hartnell notes that medieval physicians might opt for one of two contrasting approaches.

They would choose to make an incision either close to the part of the body requiring treatment or in an opposite spot on the body that allegedly corresponded to the affected organ.

Some medieval and Renaissance-period medical treatises featured detailed illustrations of the points on the body where it was appropriate to perform bloodletting incisions, depending on which body part an illness had affected.

Similar medical illustrations and practices extended as far as South Asia and the Middle East.

In medieval and Renaissance Europe, bloodletting had become so common a therapy that barber-surgeons practiced it. These individuals were men who could trim a person’s hair or beard, as well as pulling out badly damaged teeth and withdrawing blood.

In 18th-century Europe, surgeons continued to use bloodletting as a treatment for fever, hypertension (high blood pressure), inflammation of the lungs, and pulmonary edema (excess fluid in the lungs).

Some physicians had even wider uses for this allegedly therapeutic method. For example, John Hunter — one of the forefathers of modern surgery — described various other uses for bloodletting, including in the treatment of smallpox or gonorrhea.

In this latter case, he advised bloodletting by leeches, which a doctor would have to affix to the patient’s testicles.

Bloodletting was still fairly common throughout the 19th century, though by the start of the 20th century, it was gradually becoming unpopular with both the medical community and the public at large.

Speaking of this practice’s popularity in the mid-19th century, a consultant physician at that time, Dr. E. Copeman, wrote:

“In my early days, bleeding was very frequently resorted to in this hospital; and people were in the habit of coming to be bled at their own request, just as they now apply to have their teeth drawn, and it was thought to be good practice for the students.”

Bloodletting started to lose ground in part thanks to the work of French physician Pierre-Charles-Alexandre Louis, who began questionning this therapeutic method in the 1820s.

Louis’s approach was to look at the number of patients who had received this therapy and — taking into consideration the effect of other factors, such as age — to determine whether bloodletting had actually done more good than harm.

His conclusion, again and again, was that there was not enough evidence in support of the idea that withdrawing blood could improve health.

While he did not altogether reject bloodletting as a therapy, Louis wrote that according to his observations, “the study of the general and local symptoms, the mortality and variations in the mean duration of pneumonitis, according to the period at which bloodletting was instituted; all establish narrow limits to the utility of this mode of treatment.”

Despite the fact that doctors no longer prescribe bloodletting, the practice has not died out entirely.

In some communities around the world, there are people who still believe that this practice can help cure all sorts of ailments and diseases.

Leech therapy has also persisted in alternative medicine, with some arguing that it can help improve blood flow and may even have an antitumor effect.

But bloodletting’s most important legacy is, perhaps strangely, blood transfusion.

Throughout history, bloodletting has been paired closely with an interest in the various functions of the human body.

By looking into how changing the volume of blood in the body might affect its health, doctors eventually came to understand more and more about blood circulation, the importance of blood to health, and the characteristics of blood.

In the 1200s, a Persian scholar called Ibn an-Nafīs had already understood that blood flows through the veins that thread their way to and from the various organs. However, it took European scholars another 400 years or so to learn about circulation.

Doctors in Europe started to practice blood transfusions as early as the 1400s, as they were aware of the dangers of blood loss.

However, for many centuries, they lacked the knowledge that there are different blood groups with different compatibilities, which affects the success of blood transfusions.

It was Austrian physician Karl Landsteiner who, in 1909, first discovered and described different blood groups, making blood transfusion a viable therapy.

For his contribution to the field of medicine, Landsteiner received the Nobel Prize in Physiology or Medicine in 1930.

Nowadays, each year sees the collection of approximately 118.5 million blood donations globally. This donated blood helps save people’s lives and improve their health.