Information icon.svg Results for the 2023 RationalWiki Moderator Election have now been posted. Thank you for participating in this election, and congratulations to the winners!
Bronze-level article


From RationalWiki
Jump to navigation Jump to search
A scarificator — a 19th-century spring-powered bloodletting instrument creating multiple cuts in the skin at once. Ouch!
Against allopathy
Alternative medicine
Clinically unproven
We all need someone we can bleed on
And if you want it, why don't you bleed on me?
—Rolling Stones' Let it Bleed

Bloodletting is a formerly widespread medical treatment. It is famous as one of the most common treatments of prescientific humoristic medicine, which postulated that disease was caused by imbalance of the body's humors: black bile, yellow bile, blood, and phlegm. If a person had a disease which indicated too much blood, bloodletting was used to correct the problem. Bloodletting was even thought to be a cure for anaemia.[1]

Bloodletting has a long, venerable history of use in traditional and pre-scientific medicine as a panacea of sorts, and patients liked it so much, they had to be convinced not to be bled.[2][3] As such, it should come as no surprise that general-purpose bloodletting is still used in alternative medicine as part of Unani, Ayurveda, and traditional Chinese medicine. One naturopathic textbook lists all three of these systems as being acceptable bases for naturopathic practice.[4]

In modern medicine, bloodletting is known as therapeutic phlebotomy and is used in a few, very specific circumstances, such as polycythemia vera (in which the bone marrow produces excess red/white blood cells) and haemochromatosis (iron overload), to reduce the number of red blood cells. Bloodletting is not to be confused with lancing, a proper medical technique in which pus is drained from an abcess, boil, etc.


Bloodletting is known to have been used for about 3000 years.[5] Initially, disease was thought to be caused by malevolent supernatural entities, and bloodletting and trepanation were used to expel these spirits from the patient's body.[5] As time went on, however, physicians became more sympathetic to naturalistic explanations for disease, and this resulted in the Greek Theory of The Four Humors, in which imbalance of the four humors (black bile, yellow bile, blood, and phlegm) was considered the root cause of all diseases. (Bloodletting use also developed independently in India, with the bloodletting technique Sravana being described in approximately the 6th or 7th century B.C. in the Ayurvedic surgery treatise Sushruta Samhita).[6] Greek humorism spread, gradually became Europe's chief medical practice, and arrived in Asia, where it was adopted by Islamic cultures and adapted in the form of Unani in about the 10th century A.D.[7]


Fast-forward a few centuries. In 1793, there was a yellow fever epidemic in Philadelphia, and Benjamin Rush, a physician and signatory of the United States Declaration of Independence, believed he could effectively fight the disease by relieving patients of up to 75% of their blood, because he treated himself this way and got better.[8] His work A Defence of Blood-letting, as a Remedy for Certain Diseases (published in Volume 4 of Medical Inquiries and Observations[9]) contains anecdotes like the following:

I have elsewhere mentioned the advantages of bleeding pregnant women, in the yellow fever. I did not learn the advantages of the practice in that disease. I bled Mrs. Philler 11 times in seven days, in a pleurisy during her pregnancy, in the month of March, 1783; and Mrs. Kirby 16 times in the same condition, by my orders, in the winter of 1786, in a similar disease. All these women recovered, and the children they carried during their illness, are at this time alive, and in good health.

Sure, all those women recovered, but what about the ones who died after being bled? Rush would probably weakly argue that the people who died after bleeding did so only because they were too ill to be cured, so it couldn't be helped.

[Bloodletting] removes coma. Mr. Henry Clymer was suddenly relieved of this alarming symptom, in the fever of 1794, by the loss of twelve ounces of blood.

"Someone who had been in a coma for an unspecified amount of time came out of the coma an unspecified amount of time after he was bled. Therefore, bloodletting works." That's just not a convincing argument. It wouldn't be convincing even if the person woke up just a few minutes later–since Rush probably bled hundreds, if not thousands, of people, coincidences like this are to be expected. Maybe most of his coma patients didn't get better, and this one was just part of the lucky minority. Without statistics, there's no way of knowing.

I bled my eldest daughter when she was but six weeks old, for convulsions brought on by an excessive dose of laudanum given to her by her nurse; and I bled one of my sons twice, before he was two months old, for an acute fever which fell upon his lungs and bowels. In both cases, life appeared to be saved by this remedy. I could mention many more instances in which it has snatched from the grave, children under three and four months old, by being used from three to five times in the ordinary course of their acute disease.

"And absolutely none of the kids I treated died. Ever. At all. Just trust me." Also, "appeared to be saved" is right.

A boy of Mr. John Carrol owes his recovery from the small-pox to the loss of fifty ounces of blood, by five bleedings, at a time when nearly every pock on his arms and legs had a purple appearance. Louis XIV was bled five times in the small-pox, when he was but thirteen years of age, and thereby probably saved from the grave, to the great honour and emolument of the single physician who urged it against the advice of all other physicians of the court. Dr. Cleghorn mentions a single case of the success of bleeding in the petechial small-pox. His want of equal success afterwards, in similar cases, was probably occasioned by his bleeding too sparingly, that is, but three or four times.

Now, Rush obviously thinks it is inconceivable that these people could have gotten better without bloodletting. Of course, this is fallacious; thanks to statistics, we now know that about 30% of smallpox patients live. Even in Rush's day, when such detailed numbers weren't available, it was probably known that smallpox wasn't always fatal, so his belief is unjustified.

Note also that when people afflicted by smallpox die even after being bled, he simply handwaves those anecdotes away. Later in the book, Rush claims again that "moderate bleeding" is harmful, and that only "heavy" bloodletting works, giving examples of people losing from a few pounds to over 100 ounces of blood before being cured. But it must be noted that despite this, Rush was perfectly content to use an instance of "moderate" bloodletting in the coma anecdote described previously, in which only 12 ounces of blood were drained from the patient. In other words, Rush claims light bleeding is ineffective only when it is used in failed cases; if light bleeding is performed in a "successful" anecdote, he has absolutely no qualms about using that testimonial in favor of bloodletting. He thus uses this argument as an escape hatch, which he uses only when it suits him.

Positive results must be due to bloodletting and not natural improvement (despite the fact that many of the conditions he lists, including smallpox, can resolve on their own), and negative outcomes simply don't matter, because Rush said so. If someone dies, it's just because they weren't bled enough; if they had lost more blood, they would have lived. This is one of the characteristics of pseudoscience: there is no falsifiability. Every outcome only confirms the original hypothesis, and no possible result will ever disprove it. With this sort of "logic", you can believe in anything from flat earthism to mercury pills (indeed, Rush actually promoted mercury in this book in addition to bloodletting).

In the month of June of 1795, I visited Dr. Say in a malignant fever, attended with pleuritic symptoms, in consultation with Dr. Physick. An acute pain in his head followed six successive bleedings. After a seventh bleeding, he had no pain. His fever soon afterwards left him. In thus persevering in the use of a remedy, which, for several days, appeared to do harm, we were guided wholly by the state of his pulse, which uniformly indicated, by its force, the necessity of more bleeding.

Just like the temporary worsening and detox symptoms of homeopathy and naturopathy! What a coincidence.[10]

I bled Mrs. Fullarton twice in a pleurisy in January, 1804, in the 84th year of her age, and thereby cured her disease. I drew six and thirty ounces of blood, in the year 1806, at three bleedings, from Mr. Israel Jacobs in the 91st year of his age, in a bilious fever, in the course of a few days. He was cured by this remedy, and at this time, July 29, 1809, enjoys good health.

"Really, he was. Cured, that is."

It belongs to this remedy to prevent the chronic diseases of cough, consumption, jaundice, abscess in the liver, and all the different states of dropsy which so often follow autumnal fevers.

The basis for this claim is probably testimonials along the lines of "I've used bloodletting for a long time, and I haven't had a cold in years!" Of course, these sorts of anecdotes don't clarify if people who didn't get bled were more likely to get colds.

Pain is probably not connected necessarily with child-bearing. Many of the other evils inflicted upon the human race, in consequence of the disobedience of our first parents, have been lessened or eradicated by the ingenuity of man. The pain of child-bearing travelers tell us, is much lessened among the Turkish women, by their taking sweet oil (which acts as a purge) during their pregnanacy. Direct debility, whether induced by fasting or long and slow diseases, tends alike to mitigate the pains of labour. These facts have led me to inquire, whether blood-letting does not produce the same effect. I have often observed labours to be short and comparatively early, which have succeeded a fever that has been cured by bleeding. Upon my mentioning this fact to Dr. Dewees, he informed that he had often bled when parturition was slow, and that he had always found that he thereby both shortened and lessened the pains of labour.

Any reduction in pain can be easily explained as the result of the placebo effect. The supposedly shortened duration of childbirth can be accounted for by confirmation bias or by his relying on a subjective sense of time (as opposed to timing and recording the durations precisely on paper). Also, Ignaz Semmelweis would probably have a few choice words to say about sticking unsterilized sharp objects in pregnant women.

In volume 5 of Medical inquiries and observations, there are yet more anecdotes, including ones which supposedly demonstrate that bloodletting can cure rabies.


In the 19th century, however, bloodletting use declined, as a result both of statistical studies on bloodletting's efficacy being conducted (as the medical profession became more scientific and less anecdotal in outlook), as well of research on bloodletting's actual physiological effects on disease.[11]

The credit for bloodletting's disproval is often attributed to Pierre Charles Alexandre Louis, a French doctor known as "the father of medical statistics", who invented the "numerical method", a precursor to modern clinical trials, and who once said "without the aid of statistics nothing like real medicine is possible."[12][13][14] However, his work on bloodletting, though revolutionary for its time, suffered from a rather small sample size and from some methodological flaws, so that it only enabled him to conclude that bloodletting was less effective than previously thought.[15][16][17] But:[15]

Louis’s work, however, was typical of a new and critical attitude in the nineteenth century towards all traditional remedies. A number of investigators in France, Austria, England, and America did clinical studies comparing the recovery rates of those who were bled and those who were not.

Though Louis' conclusions were not that disruptive to the status quo, he was nevertheless criticized by anecdotally minded doctors who refused to believe that statistics could be superior to personal experience.[14] The idea that truly effective medicine was only now being developed, with the advent of statistics, and that the previous thousands of years of medical practice were essentially worthless, was very controversial.[18] Doctors objected that:[19]

[R]esults obtained by analyses of large groups of patients were not universally applicable to the single individual presenting in their examining room.[20]

In addition:[14]

Practicing physicians were unwilling to 'hold their decisions in abeyance till their therapies received numerical approbation.' Further, 'they were not prepared to discard therapies 'validated by both tradition and their own experience on account of somebody else's numbers.'

These views grew out of fashion, and medicine dropped its reliance on anecdotal evidence. One author writing in 1875 noted,[15]

Experience must, indeed, as Hippocrates says in his first aphorism, be fallacious if we decide that a means of treatment, sanctioned by the use of between two and three thousand years, and upheld by the authority of the ablest men of past times, is finally and forever given up.

Bloodletting's image declined, so that it became known as one of the most famous examples of the barbaric ineffectiveness of pre-modern medicine. Except in traditional medicine, where it is still, even now, considered a panacea.

Modern use[edit]

In alternative medicine bloodletting is an important part of Unani, Ayurveda, traditional Chinese Medicine, and Hildegard medicine.[21][22][23][24][25][26] In all four of these systems, bloodletting can also involve cupping.

Unani is one of the few forms of alternative medicine in which bloodletting is used according to humoristic principles. Because of this, bloodletting and leeching are used quite often, owing to the fact that there are supposedly many diseases resulting from excess blood. In Unani, bloodletting is considered a good way of detoxifying the blood.[27] Unani is probably the closest thing to the backwards, old-fashioned medicine people usually think of when they hear the word "bloodletting". Some of the diseases treated by bloodletting include headaches, migraines, eczema, conjunctivitis, cataracts, asthma, angina, pneumonia, ulcers, tonsillitis and glaucoma.[28]

In Ayurveda, bloodletting is known as Raktamoksha(na) and is claimed to be good for detoxing and stimulating the immune system. It is used for conditions such as excessive drowsiness, baldness, urticaria, rash, eczema, acne, scabies, leucoderma, chronic itching and hives, enlarged liver, spleen, gout, tumors, and genital infections.[29][30][31] But it doesn't stop there: bloodletting is also used in Panchakarma, which is an Ayurvedic therapy that involves bloodletting, vomiting, purging, enema, and herbal steam inhalation in order to clear the body of toxins and balance its energy. What's interesting is that Panchakarma is supposed to be done four times a year, even by people who are perfectly healthy, because it's supposedly necessary for maintaining one's health.[32] Bloodletting is thus used not only as a treatment, but also as a preventative!

Traditional Chinese use of bloodletting is the least drastic; it is used in the context of acupuncture and only involves draining a few drops of blood. This is supposed to be good for, among other things, sore throat, epistaxis, pain of fingers, mental disorders, numbness of fingers, loss of consciousness [compare with Rush's coma anecdote], cardiac pain, irritability, aphasia with tongue stiffness, heat stroke, infantile convulsions, feverish sensation of the palm and sole, headache, redness of eyes, stiffness of the tongue, febrile disease, irritability, pain in chest, corneal disease, abdominal distention, uterine bleeding, prolapse of uterus, hernia, enuresis, facial swelling, toothache, distending sensation of chest and abdomen, cold in leg and foot, dream disturbed sleep, mental confusion, pain in vertex of the head, dizziness, blurring of vision, aphonia, dysuria, dyschesia, deafness, pain in the hypochondriac region, nasal obstruction, epistaxis, ophthalmalgia, and shingles.[22][21]

Hildegard medicine is an obscure humoristic system of medicine invented by St. Hildegard von Bilgen. It has only a few hundred practitioners, mostly in Germany.[33] In this system, bloodletting is used to detoxify the blood and remove "bad" black bile. Hildegard medicine supposedly came to St. Hildegard in visions from God, so apparently this means God approves both of detoxing and bloodletting. Go figure.


Leeches being used on varicose veinsWikipedia.
Leczenie Pijawkami ("Leech Therapy") in Warsaw, Poland, 2014

Leeching (also known as hirudotherapy) is a form of bloodletting that uses leeches to remove blood from a person instead of a knife and cup. Leeching has, surprisingly, been found to be effective for a number of conditions,[34] and is a part of modern medicine. (As with all such treatments, it should be done under proper medical supervision, as there can be issues with hygiene. Also use of leeches on certain parts of the body is not advisable. A leech's mouth contains anti-coagulants.)

Alternative medicine, however, uses it for completely inappropriate conditions. In Ayurveda and Unani, leeching is claimed to be good for (among other things) baldness.[35][36] Also, because leeching is a form of bloodletting, it is thought to be good for detoxifying. (According to one pro-Ayurveda source, "Ayurvedic medicine has had an obsession with these creatures for centuries."[37])

"Leech" is also a Middle English word for a physician or surgeon.

Recreational bloodletting[edit]

Naturally some weirdos alternatively orientated folk like bloodletting for non-medical purposes. Here are some examples:

  • Extreme sado-masochists - that's gotta hurt! Still, no pain, no gain, as they say.
  • "Real" vampires - why be sucked off by someone when you can have someone sucking your blood? (Through a straw.)
  • War mongering - bloodletting on an industrial scale and not much fun for most of the participants.
  • Corporal mortification as a religious practice.

Some forms of self-harm may involve bloodletting too.


Just because a treatment is extremely popular and has many testimonials in favor of it does not necessarily mean that it is effective. Proponents of bloodletting, arguing for the utility of bloodletting, gave as examples many cases from their personal experience which they believed demonstrated its efficacy. They told tales of "miraculous" cures, and of patients recovering some period of time (and sometimes very soon after) the use of bloodletting, with the implication being that these recoveries must have been due to bloodletting, and that they cannot have been coincidences or due to other causes.

But anecdotal evidence suffers from a number of problems which render it untrustworthy. For instance, improbable things happen, and unlikely coincidences can and do occur all the time. Rush likely treated thousands upon thousands of patients, many of whom he probably treated several times. Out of this very large population of cases, it is certain that many unlikely and coincidental events occurred. Even incurable diseases can sometimes resolve on their own, a phenomenon known as spontaneous improvement. In addition, a patient, misdiagnosed with a disease they do not have, may attribute their survival to the treatment they used, when in fact they had either no disease, or a disease that resolved on its own.

Over the course of history, countless treatments have been considered cure-alls, including not just bloodletting, but mercury (a favorite of Rush's), lead (used in Ayurvedic and traditional Chinese medicine), tobacco, and birthwort. Many of these alleged panaceas are based on theories that contradict one another. For instance, of the many currently-used systems of hands-on healing, such as Reiki, therapeutic touch, and quantum touch, many claim to be the only effective one. Similarly, homeopaths may claim that only homeopathic water is effective for curing illness, and that ordinary water is useless, while others may claim that ordinary water can indeed cure everything. The fact that supposedly "miraculous" anecdotal evidence is invoked in support of so many contradictory therapies would indicate that it is not all that useful.

Modern forms of alternative medicine rely on the same type of pseudo-evidence as bloodletting. Just as bloodletters rejected statistics because they contradicted their personal experience, modern naturopaths and other practitioners claim that their preferred unproven and disproven treatments can cure serious diseases such as cancer or hepatitis, due to their belief that personal observation trumps numbers. Arguing that homeopathy, a treatment based on anecdotal evidence, is an effective treatment, while simultaneously stating that bloodletting, a treatment also based on by anecdotes, is ineffective, is nothing more than special pleading. Cherry picking cases that very well could be attributed to coincidence or other causes cannot be considered a reliable base on which to construct a system of medicine. One cannot just reject science and pick and choose the parts of reality that seem palatable. Down that road lies a return to humorism and the barbaric ineffectiveness of pre-scientific medicine.

See also[edit]

External links[edit]

Icon fun.svg For those of you in the mood, RationalWiki has a fun article about Bloodletting.




  1. Antique Bloodletting and Leeching Instruments - MedicalAntiques
  2. Bloodletting: an early treatment used by barbers, surgeons, Cardiology Today.
  3. In the 19th century, the doctor Henry I. Bowditch had "patients who wanted annual bloodlettings to 'breathe a vein' to maintain good health." Bloodletting Instruments in the National Museum of History and Technology, by Audrey Davis and Toby Appel.
  4. Naturopathy Embraces the Four Humors, Jann Bellamy, Science-Based Medicine.
  5. 5.0 5.1 Bloodletting Over the Centuries, Gilbert R. Seigworth, M.D.
  6. History of plastic surgery in India.
  8. Pierre Charles Alexandre Louis: Master of the spirit of mathematical clinical science, Qual Saf Health Care 2005;14:462-464 doi:10.1136/qshc.2005.016816.
  9. An extract from the work in HTML format can be found here.
  10. In homeopathy and naturopathy, it is claimed that when a condition worsens, this is only temporary, and is actually a sign that the "medicine" is working.
  11. Bloodletting Instruments in the National Museum of History and Technology, by Audrey Davis and Toby Appel. This work also suggests that an additional factor to bloodletting's decline may have been homeopaths' opposition to the harsh treatments of 19th-century medicine. Be that as it may, just because homeopaths were right about bloodletting, that does not mean they were right about homeopathy. Furthermore, even if homeopathy did contribute to bloodletting's decline, it is unlikely that, by itself, it could have caused bloodletting to be abandoned. If no developments in statistics or physiology had been made, it would have been the bloodletters' anecdotal evidence against those of the homeopaths. In this situation, with both sides having the same type of unscientific pseudo-evidence, it is highly unlikely that bloodletting could have been discontinued. After all, if people believed in bloodletting because of their personal experience (or in other words, cherry picking, since that is essentially what anecdotes are), it is unlikely that the experience of other people (also cherry picking) could have altered their views. Furthermore, the "like cures like" theory behind homeopathy is in fact quite old, stretching back thousands of years, just like bloodletting, and it didn't displace bloodletting. There is no reason to think that Hahnemann's latest iteration of this concept would have done so either. In any case, without the paradigm shift from anecdotes to statistics, bloodletting would certainly still be widely used today, homeopathy or no homeopathy.
  12. Pierre Charles Alexandre Louis, Red Gold, PBS.
  13. Sicko Statistics: Michael Moore and L’École de Paris, Gerald Weissmann, doi: 10.1096/fj.09-0301ufm March 2009 The FASEB Journal vol. 23 no. 3 667-671.
  14. 14.0 14.1 14.2 Evidence-based medicine: old French wine with a new Canadian label?, P K Rangachari, J R Soc Med. 1997 May; 90(5): 280–284.
  15. 15.0 15.1 15.2 Bloodletting Instruments in the National Museum of Sicence and Technology.
  16. Morabia, A. (2006). "Pierre-Charles-Alexandre Louis and the evaluation of bloodletting". Journal of the Royal Society of Medicine 99 (3): 158–160. doi:10.1258/jrsm.99.3.158. PMC 1383766. PMID 16508057.
  17. [1]
  18. The Therapeutic Perspective: Medical Practice, Knowledge, and Identity in America, 1820-1885, page 201.
  19. Bloodletting and the management of localized prostate cancer, J. Curtis Nickel, Can Urol Assoc J. 2011 June; 5(3): 159–160. doi: 10.5489/cuaj.11076 PMCID: PMC3114022.
  20. Compare this to the following excerpt from a homeopath's pro-anecdote article (quoted in A homeopath lectures scientists about anecdotal evidence, Orac):

    Population-based studies provide information about what’s true across enormous groups of people. They provide averages and ranges. However, they tell us nothing whatsoever about each individual.

    Ultimately, the only evidence that truly matters is anecdotal: what a treatment does to the individual. It matters not if some nonexistent average person might benefit from it. That has little bearing on the individual’s reaction. It matters not if a large proportion of people tolerate a treatment well, if the individual is made ill by it.

    The only medical evidence that truly counts for each person is anecdotal.

  21. 21.0 21.1 Bleeding Peripheral Points: An Acupuncture Technique
  22. 22.0 22.1 Treating Herpes Zoster (Shingles) with Bloodletting Therapy: Acupuncture and Chinese Medicine
  23. Chinese Blood Letting Therapy for Headaches
  24. Hildegard medicine, NATURAL HEALING GUIDE.
  25. Bloodletting, E-swastya.
  26. Unani System of Medicine Practice,
  28. Fasd (venesection): introduction,
  29. Bloodletting - An Ayurvedic perspective
  30. Raktamokshana(Siraveda & Jalokacharana), Ayurveda Health Clinic.
  31. Bloodletting therapy helps to remove toxins,
  32. Ayurveda - Panchakarma,
  33. Medical Miracle Worker, Chicago Tribune, March 01, 2000, Janet Kinosian.
  34. Most commonly being the removal of blood from reconstructed body parts, as veins cannot be surgically reconstructed yet.
  35. Ayurveda for Alopecia, AltMD.
  36. Unani Therapy (Ilaj-bil-Tadbir) to Cure Diseases
  37. Ayurvedic Detox: Leeches Help You Live Longer, Reenita's wisdom.