On this page, we’ve collected together everything you’ve ever wanted to know about the placebo effect. We’ve answered loads of questions including everything from ‘What is the placebo effect?’ to ‘Can you use placebos honestly?’. With so many placebo FAQs, we’ve had to group our questions together, so it’s easy to find what you’re looking for. The sections are as follows:

  1. About
  2. Usefulness
  3. Ethics
  4. The placebo effect in everyday life
  5. History of the placebo effect
  6. The nocebo effect
  7. Mechanisms of the placebo effect
  8. Physical diseases
  9. Psychological diseases & mental health
  10. Religion & faith
  11. Alternative Medicine
  12. Misc.

1. About

Is the placebo effect real? / Is the placebo effect scientifically proven?

The placebo effect is a real measurable effect. If the placebo effect was not real, it would not be so important in scientific research. The gold-standard of clinical research is a double-blind placebo-controlled trial. The placebo effect is a significant effect to need to be ruled out in order to establish how effective an intervention really is.

Is the placebo effect pseudoscience?

The dictionary defines pseudoscience as: “a collection of beliefs or practices mistakenly regarded as being based on scientific method”. The placebo effect is not pseudoscience. It is a core principle of the scientific method in clinical research. At times, the placebo effect can be very small, but it is present in most clinical trials, therefore, it is scientifically proven to exist. In addition, there are a number of research groups investigating the placebo effect in reputable universities all over the world: Harvard, Oxford, Turin etc. They regularly publish scientific studies on the placebo effect in reputable academic journals.

Can the placebo effect cure disease?

A cure is different from a treatment. Placebos can be used to treat conditions, but they are rarely a cure in themselves. Some anecdotal cases, suggest that the placebo effect may be able to cure certain individuals, but there is not the research and consistency to back this up. In addition, it is possible that certain people may respond more strongly to the placebo effect than others, making them more likely to experience a cure. The full potential of the placebo effect is not yet fully understood.

What is the placebo effect vs the placebo response?

The placebo effect is the amount of effect a placebo has compared to no treatment. The placebo response can be used to refer to how a person responds to a placebo, or to the percentage of people who respond to a placebo in a clinical trial. For example, if a patient is given a placebo for a headache, the placebo effect is how much their headache improves compared to how much their headache would improve if they were given no treatment. But the placebo response can refer to how the patient responds to the placebo i.e. the brain releases it’s own painkilling endorphins or the patient just subjectively feels better. If the patient was part of a larger trial, assessing how placebos help treat headaches, the placebo response could also refer to the number of patients that experience any effects from taking a placebo. These patients are also sometimes known as ‘placebo responders’.

When is the placebo effect used? / Why is the placebo effect used?

The placebo effect is commonly used in clinical trials, to assess the value of an intervention compared to the placebo. However, some research compares placebos to no treatment at all. This helps to identify ways that the placebo could be put to use in future. Currently, placebos are not an approved treatment, however, 97% of doctors do admit to prescribing placebos. Placebos are sometimes used in an effort to alleviate a patient’s symptoms. For example, a doctor may prescribe antibiotics to a patient with a viral infection, such as a cold, because the patient will feel like they are treating their symptoms and they may indeed experience some improvement in their symptoms related to the placebo effect.

Why is there no placebo effect sometimes?

Whilst we do not yet completely understand how or why the placebo effect works, research suggests that the placebos can effect chemicals and mechanisms that are already in our body. For example, placebos can help alleviate pain, by encouraging the release of our own natural painkilling endorphins. If a condition requires treatment in a way that our body cannot replicate, there is likely to be no placebo effect. This is probably the case for conditions such as cancer. Cancer is often treated by chemotherapy or radiotherapy. Our body does not contain anything similar to chemotherapy drugs or radiation. Therefore, the placebo effect would not be able to encourage the release of these things and there would be no placebo effect. Having said that, even when a placebo is unable to work in this way, it may have a psychological effect upon how a patient feels subjectively.

Why is the placebo effect important?

If you’re running a clinical trial, the placebo effect is important, because it shows you how effective your intervention really is. But at Yekize, we believe the placebo effect is far more important than that, because it has such huge potential. It is likely that every human has the ability to respond to some type of placebo effect. (I make this claim, because animals seem to respond to the placebo effect, so there’s probably an evolutionary basis for it). This means that every human has some capacity to heal themselves. If we can maximise the placebo response in every one, we may find that people react more positively to treatments and that health outcomes improve. In addition, there is a chance that the amount of drugs required could be reduced via the conditioned placebo effect. This could have huge implications in global health and access to medicine, meaning more people could have access to more affordable treatment.

Why is the placebo effect getting stronger?

That is literally the million-dollar question. Pharmaceutical companies all over the world, are finding their drugs are becoming less effective compared to placebos. this is causing huge problems in getting new drugs on the market. We do not yet know why the placebo effect is getting stronger, only that it does. Whoever answers that question may be very rich one day.

What are pure placebos?

Pure placebos are interventions or substances that do not have any benefits to health, other than the placebo effect. They are often injections or pills that contain no pharmacologically active ingredients, although a sham surgery could also be considered a pure placebo.

What are impure placebos?

Impure placebos are interventions which are effective for some conditions, but not for the condition currently being treated. For example, using antibiotics to treat a cold (a viral infection) would be an example of an impure placebo. Antibiotics can be used to treat bacterial infections, but would have no pharmacological effect upon a cold. Other examples of impure placebos include:

  • Positive suggestions
  • Using substances outside their intended purpose, for example:
    • Probiotics for diarrhoea
    • Peppermint pills for pharyngitis
    • Antibiotics for suspected viral infections inc. colds
  • Nutritional supplements
  • Non-essential physical or technical examinations, for example:
    • Blood tests
    • X-rays
  • Sub-clinical doses of effective therapies
  • Off-label uses of a potentially effective therapy
  • Use of conventional, complementary and/or alternative medicine without an evidence-base to support the effectiveness of the medication for the condition being treated

2. Usefulness

How strong is the placebo effect?

It has been hypothesised that the placebo effect may account for up to 50% of a drug’s efficacy, but we do not yet know the limits of the placebo effect. The strength of the placebo effect seems to be variable. Some individuals report significant and prolonged effects from taking placebos, whereas some people hardly respond at all. Therefore, we do not yet know exactly how strong the placebo effect is, but it is likely to be affected by individual differences, different diseases and cultural backgrounds.

When does the placebo effect occur?

The placebo effect occurs at various stages. Most obviously, the placebo effect occurs in direct response to someone taking a placebo pill, or receiving a placebo injection for example. However, studies on placebos and pain, have shown that the body starts releasing increased levels of its own painkillers before you even take the pill. It is as if the anticipation of relief initiates the placebo effect in some cases, rather than the action of taking the placebo itself.

How long can the placebo effect last?

We don’t yet know the limits of the placebo effect, but it can last for a few minutes to several weeks. There are few long-term studies of the placebo effect, but it does seem that repeatedly receiving a placebo intervention, or being conditioned to respond to the placebo treatment, does have an effect upon the longevity of the effect.

Can you use the placebo effect on yourself?

Many people do report using placebos that they know are placebos (open-label placebos) and experiencing some effects. However, it is likely that if these people choose to take placebos, they believe that they will work for them, so they may be more likely to respond. Alternatively, research into open-label placebos has so far involved an individual being prescribed a placebo by a doctor with a positive doctor-patient relationship being involved. This can have a significant effect, however, it is not yet known whether it may be possible to respond as strongly to a placebo without a doctor or other third-party being involved.

How to use the placebo effect / How to increase the placebo effect

We do not yet understand everything about how to maximise the placebo effect and how to put it to use. However, from what we do know there are some things we can do to make a difference:

  • Branding: Branded drugs often have a stronger effect than unbranded generic drugs. As they contain the same inactive ingredients it is likely that the increased cost, improved packaging and brand name all produce a stronger placebo effect.
  • Confidence: If a doctor shows confidence in a treatment or placebo, it can have a stronger effect upon the patient.
  • Conditioning: Conditioned placebo effects involve an individual (or animal) being given a treatment alongside another stimulus such as a distinctive taste or the pain of an injection. After a while, the body becomes conditioned to respond to this other stimulus and it is possible for the body to respond to the conditioned stimulus alone, as if it is the active treatment. Conditioned placebo effects can be stronger and more enduring than other forms of placebo effect.
  • Doctor-patient relationship: A positive doctor-patient relationship, wherein the patient feels listened to and cared for can have a positive effect upon the patient outcome.
  • A room with a view: This may not strictly be due to the placebo effect, but we believe it may be related, so we include it here. Research has shown that having a natural view from your hospital bed allows patients to recover more quickly and require less pain medication than those with a view of a brick wall.

3. Ethics

Is it possible to have the placebo effect without deception?

Open-label placebos are a way to use the placebo effect without deception. The patient is aware that they are taking a placebo, but they can still experience positive effects from the placebo, especially when it is coupled with an explanation of why a placebo may work for them and a positive doctor-patient interaction. Open-label placebos have been described as one of the most honest forms of treatment. Open-label placebos allow the patient to be fully informed in a way that is often not possible with other treatments when they lack the pre-requisite medical knowledge.

Is the placebo effect ethical?

Technically, the placebo effect is a neuropsychological phenomenon, so technically ethics cannot apply to it anymore than ethics can apply to other bodily functions. However, when asking ‘Is the use of the placebo effect ethical?‘ we can provide a much better answer:

Informed consent is one of the foundations of modern medical ethics. We now believe that patients should know what they are taking and that it is wrong to deceive a patient. Therefore, it is largely regarded that deceptive use of placebos is not ethical. However, it is possible for a patient to experience positive effects from a placebo even when they know it is a placebo. This is called open-label placebo. It is thought that the use of open-label placebos may be ethical as the patient can be fully informed. Having said this, if a placebo was given to an individual instead of another more effective, conventional treatment, this would be unethical, as it is likely that the patient would be harmed by being denied access to the more effective treatment. This does cause ethical issues in conducting clinical trials. In some cases, it is unethical to discontinue a patient’s treatment to give them a placebo, so instead placebos are not used in the trial and a new intervention is instead compared to the next best treatment.

4. The placebo effect in everyday life

What is the placebo effect with alcohol?

Several studies have shown that you can get drunk on placebo alcohol. One study gave people a fake vodka-tonic (flat tonic & a slice of lime) and they found that the participants began to act drunk and some showed physical signs of intoxication and impaired memory.

What is the placebo effect with coffee?

People who drink decaffeinated coffee that they believe to be caffeinated feel more energised, but also may experience physical signs such as flushed cheeks or a slight headache that are associated with drinking caffeine. Therefore, there is a placebo effect related to drinking coffee. This may also exacerbate symptoms of caffeine withdrawal in individuals who may have missed their morning coffee. Link to study on coffee and the placebo effect.

What is the placebo effect in marketing?

Branding and marketing play a part in the placebo effect. People often respond more strongly to branded versions of a drug compared to the generic version. Branded versions are often more expensive and come in much more striking packaging and have a more memorable brand name. As both the generic and branded versions contain the same active ingredients, these differences in effects are attributable to the placebo effect.

It is likely that marketing may play an even bigger role in the placebo effect and not just in pharmaceutical products. People say coca-cola tastes nicer when it’s out of a glass bottle, or their hair feels silkier when they try a new silky shampoo. Taste and touch are subjective measures, but it is possible that marketing produces an array of placebo effects in our everyday lives.

5. The history of the placebo effect

When was the placebo effect discovered?

It has been said that “until recently, the history of medical treatment was essentially the history of the placebo effect” (Shapiro). Before the advent of modern medicine, with a few exceptions, most treatments were placebos. However, at the time, many people did believe in the effects of the treatments they were providing and they were not aware that their treatments were placebos. So arguably the placebo effect was not discovered until the 18th century when various physicians began to report the phenomenon.

Who discovered the placebo effect?

In 1799, John Haygarth, an English physician, was the first to demonstrate and use the placebo effect in research. However, prior to this, another English physician, Alexander Sutherland, had become aware of the placebo effect and introduced the term ‘placebo’ (Greek for ‘I shall please’) into the English language when referring to methods used to placate, but not to actively treat a patient.

How was the placebo effect discovered?

We do not know exactly how the placebo effect was discovered. It is likely that physicians began to suspect the placebo effect after seeing patients respond in very different ways to certain treatments. John Haygarth is credited with being the first person to demonstrate the placebo effect, doing so in 1799. He wanted to test out a popular medical treatment at the time known as ‘Perkins tractors’ – pointed pieces of metal (supposedly a special type of metal) used to apply pressure to areas of the body in order to ‘draw out’ disease (see image below). Haygarth expected that these were not an effective treatment, so he decided to investigate in the first placebo-controlled trial. He created placebo versions from wood and compared the effects to the genuine metal ‘Perkins tractors’. He found that the effects were much the same, and that the effect of Perkins tractors was attributable to the placebo effect.

What is the placebo effect?
L0010940 Originals Perkins tractors. Credit: Wellcome Library, London. Wellcome Images images@wellcome.ac.uk http://wellcomeimages.org Originals Perkins tractors. Published: – Copyrighted work available under Creative Commons Attribution only licence CC BY 4.0 http://creativecommons.org/licenses/by/4.0/

6. The nocebo effect

What is the nocebo effect? / Placebo effect vs nocebo effect

The nocebo effect is the negative version of the placebo effect. The placebo effect elicits positive responses in patients, whereas the nocebo effect causes negative responses. For example, a patient who is given a placebo to improve their pain, would experience the placebo effect, but a patient who is given a placebo and told that it will increase their pain, would experience the nocebo effect.

Can the placebo effect make you sick?

When a placebo has negative effects i.e. making symptoms worse, or causing pain etc. it is generally referred to as a ‘nocebo’. If you were taking a placebo designed to make you ill, you may experience the nocebo effect and actually become ill.

Can the placebo effect kill you?

There are two ways to look at this question:

  1. Can believing in the placebo effect kill you? If you believed that an alternative treatment worked and if you experienced positive effects from that alternative treatment, you may believe that it was more than a placebo, even if it wasn’t. Some individuals may them make a decision to reject conventional treatment in favour of this alternative treatment that is fundamentally a placebo. Therefore, in this scenario, if the patient had forgone life-saving treatment, believing in the placebo effect could have resulted in their death.
  2. Can the placebo effect itself, cause death? The term, ‘nocebo effect’ is generally used when a placebo has negative effects upon a patient i.e. increasing pain, or worsening their symptoms. While there are no reliable recorded cases of patients dying purely from the expectation of death, it is theoretically possible.

7. Mechanisms of the placebo effect

What do we know about how the placebo effect works?

Research in this area is still pretty limited, but we do have some idea of how and why the placebo effect works. Firstly, we should clarify that there is not one single placebo effect, but many placebo effects. That is to say, there are many different mechanisms by which the placebo effect can work. We won’t be able to cover them all in detail here, but we can broadly outline how the placebo effect occurs:

  • Expectation: A patient expects to experience a therapeutic benefit (consciously or unconsciously). Expectation can work in two ways:
    • The positive expectations can reduce anxiety, which can affect symptoms such as pain.
    • Expectation of a positive event can activate reward mechanisms in the brain, which can relieve pain and allow the patient feel an improvement in their symptoms
  • Learning: Previous experience of effective treatments leads to substantial placebo responses. Learning can relate to two mechanisms of the placebo effect:
    • Social learning, in which people learn from the positive experiences of others, eliciting a placebo response in themselves
    • The conditioned placebo response, in which an individual is given a stimulus alongside medication, then after a while they will respond to the stimulus as if it was the active medication. This response does not continue indefinitely, but it is one of the strongest and most universal placebo effects, with even animals experiencing it.

Mechanisms associated with expectation and learning do not necessarily occur in isolation. Often the treatment experience can initiate a variety of placebo mechanisms. These placebo mechanisms can have effects upon a wide variety of bodily systems including psychology, the nervous system, the immune system and the endocrine system. To find out more about the mechanisms of the placebo effect, read ‘Placebo Effects’ by Fabrizio Benedetti.

What is the connection between the placebo effect and endogenous opioids (endorphins)?

The body contains its own opioid painkillers, these are referred to as endogenous opioids or endorphins (think endogenous morphine). It has long been known that the placebos can active the opioid system in the body, causing it to produce more or less endorphins. This is one of the key mechanisms by which placebos can modulate pain. Taking a placebo painkiller can increase the endorphins that are released, causing a physiological improvement in pain levels. But if the patient is given a drug that blocks the effects of opioids, such as naloxone (this is often given to people who have overdosed on opiates such as heroin), the placebo effect can be dramatically reduced or even eradicated and their pain levels can remain the same. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

What is the connection between the placebo effect and dopamine release?

Dopamine is a substance produced in the brain. It is one of the feel-good neurotransmitters (chemicals used for signalling in the brain). Dopamine production has been found to be highly susceptible to the placebo effect. As well as making us feel good, dopamine also has a range of other functions and is implicated in Parkinson’s disease. In Parkinson’s disease, the neurons (brain cells) that produce dopamine begin to die. This results in tremor, muscle rigidity and slowed movements. Taking a placebo can increase the levels of dopamine that are produced, reducing the symptoms of Parkinson’s disease. But this is particularly effective in the patient’s are first conditioned to respond to a stimulus. A study released in 2016, discovered that if Parkinsonian patients are given their medication (Apomorphine injection) for 4 days, they will continue to respond to placebo injections of saline for 48 hours, as if they were receiving the Apomorphine treatment. This demonstrates that the dopamine system can be manipulated by placebo conditioning and that if this is done, the amount of required medication may be reduced.

Can the placebo effect change your brain chemistry?

Yes, one of the ways in which the placebo effect works is by affecting the release of certain chemicals (neurotransmitters) in your brain. Placebos can cause an increase in dopamine, cortisol, endorphins and other chemicals, causing physiological changes that can affect a range of conditions including pain, Parkinson’s disease and inflammation.

8. Physical diseases

What do we know about the placebo effect and cancer? / Can the placebo effect cure cancer?

The placebo effect seems to work for a number of conditions, but not cancer. Cancer is caused by genetic mutations within cells that causes them to divide uncontrollably. Generally, cancer is treated by surgery, chemotherapy and/or radiotherapy. The placebo effect works by modulating levels of chemicals that are naturally found within the body. In the case of cancer treatment, there is nothing in the body that is able to replicate the effects of surgery, chemotherapy or radiotherapy. This may be why placebos do not work on cancer directly. However, placebos can help improve symptoms and side effects of cancer and its treatments, such as fatigue and nausea. It is worth mentioning that the immune system does play a role in targeting cancer cells, but often by the time cancer has been detected, the immune system is no longer able to keep the cancer under control. Lastly, one of the most famous case studies in the history of the placebo effect is the case of Mr Wright, who supposedly took a placebo treatment and his cancer went into remission. Despite further investigations, there is no other evidence to suggest that this is possible, so it’s best to take that case with a pinch of salt. If you’re interested in reading more about the case, you can find out more here. We have also written an article to outline in greater detail why the placebo effect does not work for cancer.

What do we know about the placebo effect and Parkinson’s disease?

The placebo effect is able to improve the symptoms of Parkinson’s disease, even in severe cases. It appears to do this by initiating dopamine release within the brain, the response can be measured both clinically and at the neuronal (brain cell) level. Parkinson’s disease benefits particularly from the conditioned placebo effect. In 2016, Benedetti et al. released a study that demonstrated that if Parkinsonian patients were given an injection of Apomorphine (a Parkinson’s drug) for 4 days, they would continue to respond to placebo injections as if it was the Apomorphine for another 48 hours.

Can we use the placebo effect for pain management?

Pain management makes up one of the largest areas of research on the placebo effect. Placebos are able to activate the opioid system inside the body. Taking a placebo can cause an increase in endogenous opioids (endorphins), which are the body’s own painkillers. If a opiate-blocking drug, such as Naloxone (a treatment usually given to treat overdose of opiate drugs), is given to the patient, they are unable to experience the effects of their own endogenous opioids and the placebo effect can be blocked. But placebos can help pain in other ways too: Sometimes, a patient may expect a therapeutic benefit from a placebo. These positive expectations can help to activate reward mechanisms in the brain and to reduce anxiety, which can both help to relieve pain. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

Can we use the placebo effect for IBS treatment?

IBS (irritable bowel syndrome) can be strongly affected by the placebo effect. A recent study lead by Ted Kaptchuk, demonstrates that placebos can even be used open-label for IBS. Open-label placebos are placebos that the patient knows are placebos. They are often seen as the only ethical way to use placebos in healthcare. The Kaptchuk study found significant improvements in the overall condition, symptom severity, symptom relief and quality of life in patients who were taking the placebo. The study is available here and you can find out more about open-label placebos here.

Does the placebo effect work with diabetes?

Unfortunately, we don’t yet know for certain whether the placebo effect works for diabetes or not. A few studies have been conducted, but the results have been inconclusive or not shown any improvements. If the placebo effect does have an effect upon diabetes, it is likely that the effects are very small.

Can I use the placebo effect to grow taller?

Theoretically, the placebo effect could help you to grow taller, but we probably won’t ever know for sure. The conditioned placebo effect does increase the level of Growth Hormone (GH) produced by the body. GH is involved in growth of all tissue types, but does also have some effect upon height. Therefore, it is possible that the conditioned placebo effect could help you to grow taller, but as it involves conditioning, you would have to take a drug to increase your levels of GH and then that would have to be replaced by a placebo for you to experience growth as a placebo effect. Studies have shown that non-conditioned forms of the placebo effect i.e. expectation, do not have an effect upon the levels of GH in the body. You can find Benedetti’s study on this here.

Can we use the placebo effect for dementia?

Some studies have shown that there can be a significant placebo effect in dementia. Results have shown that almost one third of people can experience significant cognitive improvements on placebos. It is possible that this occurs by increasing the levels of certain chemicals in the brain that can aid cognitive function. This article provides a nice summary of how the placebo effect is measured in dementia and here’s a great podcast on the placebo effect and Alzheimer’s disease. This is also covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

Can the placebo effect cause pregnancy?

The placebo effect cannot cause pregnancy directly, as pregnancy requires the fertilisation of an egg cell by a sperm cell and the successful implantation of this. However, placebos that mimic fertility treatments have been shown to have an impact upon pregnancy rates suggesting that the placebo effect could help people get pregnant.

Can we use the placebo effect for weight loss / obesity?

Studies have found the placebo effect may be able to help weight loss by modulating hormones involved in hunger, such as ghrelin. So placebos don’t directly cause weight loss, but they may help to reduce hunger, helping to lower calorie intake and aid weight loss. You can see the study and a summary here.

What do we know about the placebo effect and inflammation?

The conditioned placebo effect can have a significant effect upon inflammation by increasing the production of an anti-inflammatory hormone called cortisol. But other placebo effects related to expectation of a reduction in inflammation have been shown to have a much smaller effective. It is also possible that in studies where inflammation is not objectively measured, inflammation may appear to improve, by placebos reducing pain related to the inflammation. Placebos are able to relieve pain via the endogenous opioid system in the body.

What do we know about the placebo effect and autoimmune conditions?

Autoimmune conditions occur when the immune system attacks the body. This produces harmful effects such as inflammation. As we mentioned above, placebos can act upon inflammation via the production of the anti-inflammatory hormone, cortisol. There have been a limited number of studied on the placebo effect and autoimmune conditions, but animal models of lupus, arthritis and the rejection of transplanted skin grafts have shown positive responses to placebo conditioning. In humans, both lupus and multiple sclerosis have been shown to benefit from placebo conditioning, but research is still developing in this area. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

9. Psychological diseases & mental health

Can we use the placebo effect for anxiety?

Placebos often work particularly well in psychological conditions such as anxiety. Anxiety appears to be highly susceptible to the expectation of a positive outcome from treatment. Whether it’s generalised anxiety or anxiety around a specific situation, such as public speaking, research does suggest that the placebo effect can be highly beneficial. The physiological mechanisms by which placebos may affect anxiety are not fully understood, but it is thought that they may affect activity in the amygdala (the fear centre of the pain) or they may increase levels of serotonin (a feel-good hormone) that can help to reduce anxiety. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

Can we use the placebo effect for depression?

The placebo effect has been studied extensively in relation to depression. It is thought that placebos can have a psychological effect on depression, caused by the patient’s expectation of a positive outcome. But there is also evidence to suggest that placebo conditioning can be effective in depression as well. Placebos can cause chemical changes in the brain, such as increases in the ‘feel-good’ chemicals serotonin and dopamine, as well as a reduction in cortisol, a hormone related to stress and anxiety. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

What is the relationship between the placebo effect and antidepressants?

In 2008, a meta-analysis (review of several studies) found that after decades of prescribing, the antidepressant, Prozac, was only as effective as placebos. At this time, it was also suggested that the marginal improvements caused by antidepressants were not clinically meaningful and that there was little point in prescribing antidepressants for anyone but the most severely depressed. However, in 2018, a new study was released that demonstrated that antidepressants are more effective than placebos in people with moderate to severe depression. Previously the statistics had been skewed because antidepressants were commonly prescribed for mild depression, low mood or general sadness – conditions for which antidepressants are not very effective. So what does that mean for the placebo effect and antidepressants? There is a significant placebo effect associated with taking antidepressants. This may cause some improvement in depressive symptoms. However, antidepressants are stronger than placebos when prescribed correctly for moderate to severe depression. You can find the original 2008 meta-analysis and an NHS write up on the 2008 study here and here’s an NHS write-up 2018 follow-up review.

Can we use the placebo effect for ADHD?

In 2010, a study was published that demonstrated that the conditioned placebo effect can be used to reduce the amount of ADHD medication required by children. The study paired a placebo with ADHD medication, finding that the conditioned placebo effect could allow the medication dose to be reduced by 50%. You can read the study here.

How can the placebo effect be used for addiction?

The reward mechanisms in the brain are an integral part of addiction and also highly susceptible to the placebo effect. The placebo effect can increase the pleasurable effects of a drug, but the same results have not been found in alcoholism. Conversely, nicotine-containing products such as cigarettes has a very high relationship with the placebo effect. People who believe they are smoking a nicotine-containing cigarette, but who are in fact smoking a nicotine-free cigarette, can still experience similar effects to nicotine. In addition, placebos can help to relieve cravings and withdrawal symptoms in people trying to quit smoking. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

10. Religion & faith

What do we know about the placebo effect and faith healing?

This is evidently a controversial topic. Scientifically, we understand of no other mechanism by which faith healing could occur than by the placebo effect, however that does not mean that no other mechanism exists, just that the best answer science has currently come up with is that faith healing is the placebo effect. In addition, reports of faith healings sometimes describe dramatic events and total cures, which are rarely observed from the placebo effect. Many religious individuals – including scientists – may be uncomfortable with this knowledge. Some religious people reconcile this by choosing to believe that the placebo effect is the mechanism which God uses to heal people, in reward for their faith. At Yekize, we respect people’s beliefs and we are open to listening to the perspectives of others on these matters.

Do you need to have faith in a treatment for the placebo effect to work?

Until recently, it was believed that you needed to have faith in a placebo intervention to experience the benefits of the placebo effect. However, research into open-label placebos (placebos that you know are placebos) has proven that you can respond positively to placebos even if you know you are taking them. In addition, the placebo effect has been proven to work on animals after a period of conditioning. It is generally considered that faith and belief are thought processes that animals do not possess, therefore, this may be considered further evidence of the placebo effect in the absence of faith.

How can I reconcile the placebo effect with God & my religion?

Many religious people struggle to reconcile the existence of the placebo effect with their religion, especially when their beliefs include miraculous healing events. Some individuals choose to believe that healing miracles are not related to the placebo effect and that they are two distinct phenomena. Others choose to believe that the placebo effect is the mechanism which God uses to heal people, in reward for their faith. At Yekize, we welcome you to engage with us and to share your thoughts on these matters, whatever your religious beliefs.

11. Alternative Medicine

What do we know about the placebo effect and alternative medicine?

Amongst scientific circles, it is generally regarded that alternative medicine is the placebo effect, with a few exceptions. Alternative medicines have rarely gone through placebo-controlled trials, but where placebo studies have been done, it is often found that the effects of alternative medicine are comparable to those of the placebo effect. However, that is not to say that you should not use alternative medicine. Alternative medicine may be a useful means for a large number of people to access their own placebo mechanisms. We recommend that if you do use alternative medicine, you do so alongside conventional treatments if it’s anything serious.

Is there a difference between the placebo effect and hypnosis / hypnotherapy?

Hypnosis and the placebo effect are not the same thing. Hypnosis requires a patient to be hypnotisable, which is a measurable characteristic. On the other hand, response to the placebo effect does not correlate with hypnotisability. However, the clinical results of hypnotherapy are not always related with hypnotisability. Hypnotisability is a factor when hypnosis is used to treat pain and anxiety, but it is not in addiction or habit disorders. Grünbaum’s theory of the placebo effect allows an intervention to be defined as ‘non placebo’ “if it can be demonstrated that its effects reproduced according to the theory upon which the therapy is based”. Therefore, it could be said that hypnotherapy is not a placebo for anxiety and pain, but it is a placebo for addition and habit disorders. This original study from 1990 is available here.

Is there a placebo effect with acupuncture?

There have been a large number of studies comparing the placebo effect with acupuncture. Generally, it is thought that the effects of acupuncture are attributable to the placebo effect, which can be very powerful in some cases. However, there is still some debate as to whether acupuncture has its own effects outside the placebo effect, especially as a specific type of acupuncture – verum acupuncture – has been shown to be more effective than a placebo. The study of acupuncture is incredibly complex and susceptible to bias, which may be why we don’t have a stronger conclusion yet. Here’s a scientific review of acupuncture and the placebo effect and the bias that may exist.

12. Misc.

Is the placebo effect a confounding variable?

A confounding variable is a variable that was not accounted for initially when an experiment was planned. This can introduce bias or suggest there is a correlation, when in fact there isn’t one. Therefore, if you designed an experiment, but did not analyse the placebo effect it could become a confounding variable in your study.

Can you clarify the placebo effect vs Hawthorne effect?

The placebo effect is the effect of an intern substance within the context of the ritual of the therapeutic act. The Hawthorne effect is the alteration of behaviour in a group of people in a study, because they know they are being observed. The Hawthorne effect can produce effects that look like the placebo effect, but it is a different phenomenon entirely. This is covered in more detail in ‘Placebo Effects’ by Fabrizio Benedetti.

Is there a placebo effect in animals?

Numerous studies have demonstrated that the placebo effect is present in animals. The best examples of this have been in studies looking at the conditioned placebo effect. In these studies, animals are given an active drug along with a stimulus, such as a sweet taste. After a while, the animals will to respond to a placebo with the stimulus as if it was the active drug.