Medieval Phlebotomy


For some reason I had assumed that bloodletting wasn’t very common in the Middle Ages, but my current reading about medieval medicine has set me right. Even in the early Middle Ages it was far from unusual.

Bloodletting is a logical consequence of accepting that illness is caused by an imbalance of the humours. As medical texts from the Greek and Arabic-speaking worlds were translated into Latin from the twelfth century onwards, it became even more important as one of the physician’s many skills. Bloodletting was carried out by both surgeons and physicians, even though it was technically a surgical procedure.

One of the purposes of bloodletting was to allow the physician to make a diagnosis. An instruction book, probably written by Maurus of Salerno in the twelfth century, told the physician what to look for in the blood he collected from his patient. The physician was to examine it before, during and after coagulation. He was to look for viscosity, hotness or coldness, greasiness, taste, foaminess and speed of coagulation. You’ll note that this required him to do a bit more than just look at the blood.

The main purpose of bloodletting was to treat diseases by restoring balance between the humours.  All the four humours were present in blood, so an excess of one of them could be removed by drawing off some blood.

The most common place for bloodletting was the arm, in which there were three major veins: the cephalic, the median and the basilic. If the diagnosis was that the patient was melancholic, however, a vein in the forehead was more likely to be cut. The veins in the thumb were associated with pains in the head and the vein between the ankle and the foot was linked to diseases of the genitals.

There were detailed instruction books available to physicians telling them how to tie the arm to prepare the vein and how to make the cut. There were also instructions about how to avoid nerves and arteries near the site of the incision. The manuals also told them how to limit the bleeding when they were finished.

The patient’s diet before and after the bloodletting was important, as were the seasons of the year, the phases of the moon and the time of day when the procedure was carried out. Charts like the one above, which showed where on the body cuts should be made for bloodletting, often included diagrams of astrological influences on the patient. Each sign of the zodiac had power over a specific part of the body and the diseases that affected it. In the fourteenth century, physicians would consult an astrological table to find out when there was a favourable alignment in the heavens for the exact procedure they were proposing. Knowing where the moon was in relation to the signs of the zodiac meant that the physician knew where to cut, since the moon and the other planets drew the humours to different parts of the body. The physician had to examine astrological tables and calendars to hand before he could decide what to do.

There were other things to think about as well. Was it better to remove a lot of blood in one go or to make a number of incisions over a period of time? Should the blood be taken from the afflicted area or from the opposite side of the body to encourage the blood to move away from the site of the disease?

Most medieval practitioners were aware of the risks associated with bloodletting. They were advised that blood should not be taken from small children, pregnant women, the old or the weak. Although they didn’t know what caused it or what it really was, they also knew about the risk of infection. They didn’t know how to prevent it, though, and there was little they could do once a cut became infected.

Despite this, some people had regular bloodlettings. In the late twelfth century,  Peter the Venerable, Abbot of Cluny, wrote a letter to a medical expert asking for help with an illness of long-standing and mentioned that he had put off his bi-monthly bloodletting. He was obviously someone who believed in the preventative efficacy of bloodletting, which was a common practice for those wealthy enough to be able to look after their health. Blood was a warm and wet humour, and bloodletting could make the patient cooler and drier, ready to face a hot summer.

Leeches were also used for bloodletting, but very rarely. I couldn’t even find them listed in the indices of the reference books I used.

Sadly, despite its popularity, bloodletting achieved nothing other than, in some cases, weakening the patient. It was many centuries, however, before the practice was challenged.


Medieval Bodies by Jack Hartnell

Medieval and Early Renaissance Medicine by Nancy G. Siraisi


April Munday is the author of the Soldiers of Fortune and Regency Spies series of novels, as well as standalone novels set in the fourteenth century.

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Filed under Fourteenth Century, Medieval Medicine, Twelfth Century

28 responses to “Medieval Phlebotomy

  1. Fascinating. I had no idea about the release of blood from different areas of the body to treat different problems. I wonder how the blood letting chart compares to an acupressure or acupuncture chart? Got me thinking yet again April. Great post.

    Liked by 3 people

  2. So fascinating, and being an ex op theatre nurse I can confirm it’s a load of baloney 😊 however I wonder if in another 400 yrs time they’ll look back at our medical and surgical procedures and say the same thing. They did the best they could with the little knowledge they had.

    Liked by 6 people

  3. Yikes! I would not have done well as a patient at that time. I almost passed out reading this. Well written, but making me happy to be born in the 1900s

    Liked by 7 people

    • lydiaschoch

      I had the same reaction, Dan!

      Liked by 4 people

      • It definitely curdled my blood. I’d have been a most reluctant patient. It amazes me so many survived serious wounds though – they either had a massive amount of luck or some of the people treating the wounds got it right. As for those who apparently survived trepanning – I’m shuddering as I type! And cataract surgery with no antibiotics or pain relief.
        Have you ever read Pepys’ account of his operation? It may have beena few centuries later but it was brutal.

        Liked by 3 people

        • Trepanning was an incredible process, although I can’t understand how anyone could have been persuaded to have it done to them. I’ve got a book which has lots of illustrations from a fourteenth-century surgeon’s handbook and some of those are very disturbing, especially when you remember that the patients were conscious.

          I don’t think I’ve read Pepys’ on his operation. I’ve read bits of the diary where he complains about the pain he’s in, but not the part where he describes the operation.

          Liked by 3 people

          • I can only think he was in so much pain, he didn’t think the operation could be any worse.

            As for trepanning! Quite simply – NO! Had that been me, no one would have been able to hold me down long enough, lol. I know this because, as a very small child, it took four nurses to hold me down for a simple injection, haha. As an adult facing trepanning, I suspect I would have found superhuman strength to fight. It hardly bears thinking about, does it?

            Liked by 3 people

    • I tried not to think too much about how it might have felt to have been bled, but I’m also very glad to have been born in the last century.

      Liked by 4 people

  4. Bloodletting was once a treatment given by Alf Wights’ partner (Sigfried Farnon of the James Herriott books). It was seemingly effective for a horse with severe laminitis. He drained away a considerable amount of blood & had the owners soak the hooves in an icy beck between walking sessions. No other treatment was given.

    Wight was not sure if the bloodletting was the reason, but the horse recovered from a serious ailment that would have probably caused it to be put down. Wight chose to never try bloodletting, preferring modern hoof treatments.

    Bloodletting still has uses in a few human blood diseases. Three noted by the British Columbia Medical Journal are: hemochromatosis, polycythemia, and porphyria cutanea tarda. It also notes bloodletting is used to decrease iron levels in certain organs.

    A good many ancient treatments have come back. Herbal compounds come to mind, as well as acupuncture and acupressure. However, I hope calomel, arsenic and other metallic derivatives will stay in the past forever.

    One never knows. Much of what goes around comes around!

    Liked by 2 people

    • Cupping was popular in the Middle Ages and is enjoying a bit of a comeback, although I believe it didn’t go away in some parts of the world. Most of what I’ve read about it suggests that it’s not a good idea, but people enjoy fads.

      Liked by 1 person

  5. Interestingly I had never associated astrology with blood letting. It always surprises me just how much astrology permeated the medieval culture.

    Liked by 4 people

  6. In the days when I was a blood donor, I used to experience a mild high after I’d donated, and I could never work out if that was the result of having been bled or because I felt virtuous. I knew others who said, oh, I feel so good after I’ve done it.
    It’s a pity the medieval surgeons and physicians didn’t make more use of leeches – the risk of infection might have been lower.
    And I agree with you about the lack of questioning of ancient practices, and it seems to have got worse before it got better. Renaissance physicians clung to practices from ancient Greece. Tudor housewives seem to have kept the equipment they used in their dairies cleaner than surgeons did their utensils.

    Liked by 3 people

    • It’s a wonder to me anyone survived at all.

      I never felt a high after giving blood. I hated it, but I’m not bog standard type O, so I persevered until they told me to stop. I don’t know that I even felt virtuous. I wasn’t sorry to stop, though.

      Liked by 2 people

    • I never felt anything after donating until I started having reactions to the anticoagulants. Gutted it out to the 5-gallon point & had to stop. Sure feel guilty.

      Wonder if leeches fell out of favor for religious reasons? Were they easy to come by in England? Here in Indiana, they’re common in swampy areas. (I just don’t think of England as a place with the kind of mucky swamps that we have here.) Never personally encountered them in lakes and rivers, nor saw anyone who did. (Thank goodness! I’d probably keel over.)

      I’ve heard they’re gaining popularity as a way to reduce haematomas. I’ll just use cosmetics. Ick!

      Liked by 2 people

      • Well done for persevering with giving blood for as long as you could.

        There were many more marshy areas in England in the Middle Ages than there are now, so it’s possible there were some varieties of leech that liked blood. Given that a Middle English and Saxon word for doctor was ‘leech’ (but spelled differently), my guess is that there were leeches around for bloodletting.

        Liked by 1 person

      • I’d heard leeches were making a medical comeback, too. I’ve never seen one, but I find them fascinating.

        Liked by 2 people

  7. Eek eek EEK! My thought process while reading this, lol. I was aware of bloodletting being a common medieval treatment option, but I didn’t know about the astrology applications or strategically employing different areas of the body, let alone the preventive uses. Excellent, eye-opening post! Reaffirmed what I knew and built upon it.

    Liked by 3 people

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