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What is the Placebo Effect – Causes & Examples 

Published by at August 17th, 2023 , Revised On October 5, 2023

Imagine taking a sugar pill, believing it to be a powerful painkiller, only to find that your headache disappears shortly after. This phenomenon, where an inactive or sham treatment improves symptoms, is known as the placebo effect. 

While it has mystified researchers and clinicians for decades, the placebo effect is essential in understanding the human mind, cognitive bias, and its impact on health. Let’s explore the causes and examples of this intriguing effect.

What is the Placebo Effect Meaning?

A placebo is a substance or treatment with no therapeutic effect, often used in clinical trials as a control. Drawing from a scholarly source, it is designed to mimic the experience of receiving an actual medical intervention but has no active ingredients or therapeutic action. 

Placebo Effect Definition

The placebo effect psychology phenomenon is where patients experience genuine improvements in health or relief from symptoms simply because they believe they are receiving treatment. 

This sometimes stems from what some call actor-observer bias, where the individual being treated (the actor) experiences symptoms differently than an observer would interpret them.

In research, comparing the effects of a placebo to an active treatment can help determine the treatment’s real efficacy, as any difference can be attributed to the active substance or intervention. Placebos underscore the intricate connection between mind and body. 

Placebos underscore the intricate connection between mind and body and highlight the dangers of confirmation bias, where researchers and patients might interpret outcomes based on their pre-existing beliefs.

How does the Placebo Effect Work?

The placebo effect is a fascinating phenomenon that illustrates the power of belief, perception, and the mind-body connection. This is particularly interesting when considering our inherent bias for action, where humans prefer action to inaction, possibly enhancing the placebo response when given some form of treatment. 

Though it is primarily understood as a psychological occurrence, the mechanisms underlying the placebo effect are intricate and multidimensional.

Psychology Placebo Effect

At the heart of the placebo effect is the human belief system. When an individual expects a pill, procedure, or some form of treatment to work, this belief can manifest as physiological changes. However, one has to be careful not to misconstrue this as an affinity bias, where individuals might prefer treatments that are familiar or resonate with personal beliefs.


A significant driver behind the placebo effect is the expectation. The brain may produce pain-relieving chemicals if a patient believes a pill will alleviate pain.

Classical Conditioning

Our bodies can be trained to respond to certain stimuli. Just as Pavlov’s dogs salivated at the sound of a bell, if someone takes a pill and feels better several times, their body might automatically start feeling better the next time they take the same pill, even if it is a placebo.

Neurobiological Mechanisms

Recent scientific research using advanced techniques, like neuroimaging, has provided insights into how the brain changes under the influence of placebos.

Endorphin Release

One theory proposes that when an individual expects pain relief from a placebo, the brain releases endorphins, which are natural painkillers. These chemicals can produce effects similar to opioid drugs.

Brain Activation Changes

Brain imaging studies have shown that placebos can activate the same pathways in the brain as active medications. For example, the placebo effect has been seen to influence the activity in areas of the brain associated with mood and pain perception.

Social and Contextual Factors

The way a medical professional presents a placebo can influence its effectiveness. The source evaluation method, which helps determine the credibility of the information, can come into play. If the source (like a trusted doctor) is deemed credible, the information (or treatment, in this case) may be taken more seriously.

Positive reinforcement from doctors or nurses, combined with a patient’s experiences and the perceived authority of medical environments, can amplify the placebo response.

Doctor-Patient Relationship

A strong, trusting relationship between a doctor and a patient can increase the likelihood of the placebo effect. However, if there is a ceiling effect at play, further increases in the positive nature of the doctor-patient relationship might not necessarily yield bigger placebo effects.

Positive affirmations and a confident demeanour by the healthcare provider can set strong positive expectations.

Presentation Matters

The colour and size of placebo pills, the branding of the medication, the price, or even the invasiveness of a sham procedure can influence the potency of the placebo effect. For example, drawing from a secondary source that cites a primary source research article on placebo pill colour impacts, one might find that red pills are often perceived as stimulating. In contrast, blue pills are seen as calming.

Cultural and Ethical Implications

The use of placebos raises ethical concerns. These can be complicated when considering the pygmalion effect, where higher expectations from doctors can lead to increased patient performance (or healing).

Furthermore, suppose the science community only publishes studies where placebos have significant effects and neglects others. In that case, we may fall prey to publication bias and skew our understanding of the true impact of placebos.

The cultural background can influence how one responds to a placebo. Certain treatments might be perceived as more potent in some cultures, leading to a stronger placebo effect.

However, the use of placebos raises ethical concerns. 

Administering a treatment that isn’t real could be viewed as deceitful. Yet, if the placebo provides relief, is it wrong? Thus, Medical practitioners are caught in balancing ethical integrity with patient well-being.

Anti-Placebo Effect

The opposite of the placebo effect is the nocebo effect. If someone expects a negative outcome from a treatment or pill, they might experience adverse effects, even if the treatment is inert. Negative beliefs and expectations drive it.

Evolutionary Perspective

There’s an evolutionary argument for the placebo effect. Some researchers theorise that in times of scarcity, our ancestors might not always have had access to medicinal remedies. In such situations, the ability to experience relief from symptoms, even if only from a belief in the efficacy of a non-existent treatment, would have been beneficial.

What are Some Placebo Effect Examples

Here are some examples of the placebo effect:

Pain Relief

This is one of the most studied placebo effects. Some patients given a sugar pill, believing it to be a painkiller, have reported reduced pain.


Some clinical trials for antidepressants have found that patients receiving placebos sometimes report symptom improvements.

Parkinson’s Disease

Studies have shown that some Parkinson’s patients receiving a placebo, thinking it is real medication, show increased dopamine release and improved motor function.

Irritable Bowel Syndrome (IBS)

Some patients have reported improvements in IBS symptoms after receiving a placebo treatment.


In certain trials, many migraine sufferers have reported relief from their symptoms after taking a placebo.

High Blood Pressure

There are instances where patients with high blood pressure showed improvement after receiving a placebo treatment.


Some people have reported getting better sleep after taking a placebo they believed to be a sleep aid.

Chemotherapy Side Effects

Some patients have reported fewer side effects from chemotherapy after being given a placebo they thought would help with those side effects.

Joint Pain and Arthritis

There are reports of patients experiencing relief from joint pain after being treated with a placebo.

Placebo Surgeries

In some cases, patients who underwent “sham” surgeries (procedures where no actual surgical intervention was done) reported improvements similar to those who underwent real surgeries.

What is the Downside of the Placebo Effect

While a placebo effect can be beneficial in certain contexts, it also has downsides:

Misinterpretation of Treatment Efficacy

If a treatment’s effects are purely or largely due to the placebo effect, it may be wrongly assumed that the treatment is effective. This can be problematic in clinical trials if the actual drug is not significantly more effective than the placebo.

Delayed Proper Treatment

If people believe they receive beneficial treatment due to the placebo effect, they may delay seeking more effective, evidence-based treatments. This can result in worsening conditions, especially in the case of serious illnesses.

Ethical Concerns

Administering a placebo, by definition, involves some level of deception. This can be ethically contentious, especially if the patient is not informed or the treatment involves more than minimal risks.

Waste of Resources

Suppose the placebo effect leads to the widespread use of ineffective treatments. In that case, it can significantly waste time, money, and other resources that could be better allocated to effective interventions.

Physical Risks

Some procedures carry risks even if they don’t provide a therapeutic effect beyond the placebo. For instance, a sham surgery might still carry risks of infection or other complications.


If symptoms improve due to the placebo effect, it may mask the underlying condition and make it harder for healthcare professionals to diagnose and treat the real issue.

Economic Implications

Ineffective treatments that sell based on placebo-driven results can make consumers unnecessarily spend money.

Dependence on Belief

The efficacy of the placebo is, to an extent, dependent on the patient’s belief. This means its effects can be unpredictable and may not always be relied upon for consistent therapeutic benefit.

Potential for Misuse

Unscrupulous companies or practitioners may exploit the placebo effect, promoting treatments they know are ineffective for profit.

Emotional Impact

Discovering that one’s improvement was due to a placebo can be emotionally challenging for some people, leading to feelings of betrayal or embarrassment.

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Future of Placebo Research

Research into the placebo effect is ongoing. As we dive deeper into understanding our brain’s complexity and the interconnectedness of the mind and body, we hope this knowledge will lead to better patient care. By harnessing the positive aspects of the placebo effect, medical professionals may be able to enhance the efficacy of real treatments and improve patient outcomes.


It is worth noting that the placebo effect doesn’t mean people are “making up” their improvements. The brain is a powerful entity, and the expectation of benefit can lead to real, measurable changes in the body. However, the placebo effect varies greatly among individuals and isn’t consistent across all conditions.

The placebo effect underscores the profound connection between our beliefs and physical well-being. While it remains an ethically contentious tool in medical settings, its very existence challenges our understanding of healing and highlights the intricate dance between the mind and body. 

As science advances, unravelling the mysteries of the placebo effect might pave the way for innovative therapeutic approaches that capitalise on the power of belief.

Frequently Asked Questions

The placebo effect occurs when a person experiences a benefit after receiving a treatment with no therapeutic value, often due to their belief in the treatment’s efficacy. This psychological response can manifest in physiological changes, highlighting the mind’s powerful influence on the body.

No, the placebo effect cannot cure cancer. While belief in treatment can influence symptoms and improve quality of life through the placebo effect, it does not eliminate cancer cells or reverse tumour growth. Proper medical interventions are essential for treating cancer. Relying solely on placebos would be dangerously misleading.

The placebo effect is not deadly, but relying solely on a placebo instead of genuine medical treatment can be dangerous. If a serious condition is left untreated because one believes a placebo is working, the untreated illness or condition can worsen and potentially lead to death. Always seek professional medical advice.

No, the placebo effect cannot cure cancer. While it might influence perceptions of symptoms and improve well-being due to belief in treatment, it does not eradicate cancer cells or halt tumour growth. Relying on placebos instead of established treatments can have serious consequences. Professional medical intervention is vital for cancer care.

Surprisingly, the placebo effect can still work even if individuals know they are taking a placebo. Some studies suggest that openly prescribed placebos can improve symptoms in various conditions. This phenomenon suggests the body’s response to the act of treatment might be as important as belief in a specific intervention.

About Owen Ingram

Avatar for Owen IngramIngram is a dissertation specialist. He has a master's degree in data sciences. His research work aims to compare the various types of research methods used among academicians and researchers.