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All You Need to Know About Placebos and the Placebo Effect

My early interest in science led me to a BSc in Life Sciences from Liverpool University, then an MSc in Health Psychology from Southampton

Table of Contents


The Definition of a Placebo

The word "placebo" comes from the Latin placebo meaning "I shall please", which leads to a definition of pleasing or placating patients. This, though, gives an indication of only one aspect of the term. There are several possible definitions but probably the most general is that of a panacea, a solution for all problems. There are, however, other more or less precise definitions:

  • a symbol of healing
  • a dummy treatment
  • a treatment without substance

The Placebo Effect

The term placebo is the "treatment" but this is different from the placebo effect which is the expected result of taking that treatment. You cannot necessarily foresee that there will be an effect, and indeed it may not be a beneficial effect.

Most people who do research consider the placebo effect to be an unwanted outcome in a clinical trial. You can deduce this from the fact that all trials of new drugs or treatments must have a way of controlling or allowing for the placebo effect. The researchers do not want their results to be skewed by unexpected effects that aren't directly caused by the treatment under investigation.

Although researchers have acknowledged its sometimes powerful existence for many years, hence the provision in clinical trials, very few people have done any specific research on the subject. It was first ignored, then controlled, then eventually studied in its own right.

In 1955, Henry Beecher found that as many as 35% of patients demonstrated a placebo effect.


The Stronger the Treatment, the Stronger the Response

Some studies have shown that the placebo effect is about 50% of the expected effect of the active drug. In other words if a drug gives, say, 90% relief from pain, patients taking a placebo but thinking they may be taking that drug may show a roughly 45% reduction in pain.

It follows that the more powerful the drug, the more powerful will be the placebo response.

Even more interestingly, a recent study reported in the January 2015 issue of Neurology, demonstrates that the perceived cost of the drug has a major role to play. An expensive drug produced a more pronounced response than a cheaper drug. In fact in this study, both the expensive and the inexpensive treatment were placebos.

Another striking effect is that of the colours of a medicine. People perceive different colours in different ways, restful, warm, and so on, so as a result of this phenomenon drug companies use different colours for different drugs. For instance, sedatives which should be calming will look markedly different from antibiotics which need to fight!

The Doctor-Patient Relationship


The doctor-patient relationship has been known for a very long time to have great importance in a patient's response. George Bernard Shaw wrote the play "The Doctor's Dilemma" in 1911 in which he describes the doctor's personality: "Even broken bones it is said, have been known to unite at the sound of his voice".

Although there hasn't been a great deal of study on the doctor-patient relationship, the general consensus is that a combination of a variety of factors come together to produce the phenomenon. The respective attitudes, expectancies and beliefs, even the surroundings (such as in a clinic or at home), all have a part to play.

The Role of Ritual in the Placebo Effect

Shamans, medicine men/women, and early healers made use of herbal remedies, but were well versed in using ritual and beliefs. With the benefit of a more modern perspective, it seems that they made great use of the placebo effect.

Their rituals and ceremonies, along with a belief that their healing powers were supernatural and given by spirits, produced cures in cases where no potions or medicines were used. In many ways it's not dissimilar to a very strong doctor-patient relationship.

For Native Americans, traditional medicines could not protect them against snakes, bears and ghosts. These vulnerabilities produced anxieties such that people experienced illnesses such as snake-sickness which could be "caught" from crossing the path of a snake. This would seem to be, from our modern day perspective, a good example of the nocebo effect: an illness was expected and it arrived.

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In modern medicine, the mere act of administering the therapy could be regarded as a ritual but probably the strongest ritual is that of the doctor's touch. Abraham Verghese gave a TED talk on this very subject.


The Ethical Controversy

There is a great divide in the controversy about placebos and their effect because on the one hand there are potentially great advantages to be found by administering people with inert substances or dummy treatments. On the other hand there is the feeling that the effect is based on a lie.

Some consider the positive aspects should be put to good use but this then brings up the question of ethics. Is it ethical to deceive a patient knowingly? Some may argue that the undoubted benefits would justify this deception and that the end justifies the means.

If however you consider that the doctor, rather than setting out to deceive, is merely choosing the treatment that will be of most benefit to the patient, maybe there is no deception involved. This is really not acceptable nowadays when patients expect full information about their treatment.

It may be possible to be perfectly open about the administration of a placebo as we can see in clinical trials where patients give fully informed consent. They always know that they may be receiving an inert treatment and yet they still do produce a placebo effect.


The Nocebo

The expected result of a placebo effect may not necessarily occur or may not even be beneficial. To take a non-beneficial effect one step further, this may actually produce a harmful result, which is known as a nocebo, .

We can see that sometimes an expectation of sickness can in fact lead to sickness. We could call this a specific form of the nocebo phenomenon: a patient expects a particular negative outcome and does indeed suffer it. An example might be, in an extreme form, that a patient expects to die during surgery. If the patient then does die but not as a result of the surgery, that would be called a nocebo effect.

In a more general form, the patient might be generally pessimistic without the pessimism being targeted at any particular outcome.

We need to distinguish between a negative placebo side-effect and a nocebo effect. A placebo can cause a negative side-effect even when it is expected to heal whereas a nocebo effect is the result of the expectation of sickness.


Why is There a Placebo Effect?

Pain and the feelings associated with being ill are the body's defence mechanism. They bring attention to the fact that there is something wrong.

Why then would we have an inbuilt placebo reaction? This would seem to combat the body's system of alert and therefore not at all beneficial to mankind. So why does that effect exist and work?

This is very much better explained by the next video produced by the Royal Institution.

I studied Health Psychology for my MSc and the subject of the placebo effect was a very small part of it, but one I found particularly interesting. I bought the text book below, The Placebo Effect, from the small academic bookshop in the hospital where I worked at the time. I found it fascinating then and it remains fascinating to this day.

It's an academic book so it requires a certain amount of concentration, more in some places than others, but it does contain some excellent discussions on the subject if you would like to explore it further.

My main source


Mel Carriere from Snowbound and down in Northern Colorado on January 03, 2017:

This truly is a fascinating subject whose further exploration would provide useful insights into how the human organism really works. Great article.

Jasmeet Kaur from India on January 30, 2016:

Very informative and helpful

SheilaMilne (author) from Kent, UK on September 30, 2015:

Thank you for that! It's a subject I find endlessly fascinating. I miss my days in medical research.

Jerome Chiaro from Costa Mesa, California on September 30, 2015:

great article. nocebos or anti-placebos are interesting as well, and rarely discussed I'm glad to note that you included this as many people are not aware of nocebos.

SheilaMilne (author) from Kent, UK on March 27, 2015:

Thanks for your comment, travmaj. It was from working in a School of Medicine that prompted me to find out more. It is indeed a fascinating subject (so too are doctors' bedside manners!)

travmaj from australia on March 26, 2015:

Most informative and interesting. I also find the placebo fascinating. I worked on a medical study many years ago. I have a friend who is involved in a study where they are given a drug or the alternative placebo. No idea what the outcome will be - except interesting.

The doctor/patient relationship amused me. I love the quote from George Bernard Shaw. I worked for a doctor for many years and was always impressed how reassurance could make a difference .Thanks for this most interesting piece.

SheilaMilne (author) from Kent, UK on March 11, 2015:

Thank you very much! I find the whole topic fascinating too.

Miran Shuleta on March 10, 2015:

I always found the placebo effect to be a fascinating method, and also surprised at how often they actually work. A very interesting piece indeed.

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