Center for Research on Ingredient Safety

What is a placebo?

In research, a placebo is an inert substance designed without therapeutic value. A placebo is given to an individual typically during a clinical study as part of a control group.
 
In a clinical study, the placebo prevents the recipient and other study participants from knowing (with their consent) who receives active vs inactive treatment protocols as the study results could be skewed if people know which treatment they received.

What is the placebo effect?

In a clinical setting, 

•  

  if someone receives no treatment, there will be no response;
• if someone receives a treatment such as a new medication, they will have a pharmacological response;
• if someone receives a placebo (without knowing whether he/she receives a new medication or placebo) and has a response similar to what would be expected from the new medication, it's called the placebo response.  

The difference between no treatment and a placebo response is the placebo effect. To put it simply, the placebo effect is the response someone experiences from "treatment" with an inert substance, which is likely due to expectation, desire, and emotion. 
 
For example, if someone was given an inert pill and was told the pill would reduce their pain, they may report less pain after taking the inert pill. 
 
Outside of a clinical setting, the placebo effect may explain why some people feel their health is positively impacted after taking supplements, using products, or undergoing procedures that have not been scientifically demonstrated to be effective. 

Why does it work?

Research shows that placebo effects are genuine psychobiological events, meaning our mind and body possess many different mechanisms that allow us to experience the positive health impact of placebo treatments (1,2).
 
While there are many mechanisms that can be responsible for experiencing a placebo effect, broadly, there are two main mechanisms: psychological and neurobiological.
 
Psychological mechanisms include expectancy and classical conditioning.

Expectancy occurs when a person expects a certain outcome and then perceives that outcome. For example, they believe the treatment will reduce their pain, then they perceive lower pain levels.
 
Classical conditioning occurs when our bodies learn to respond to a specific stimulus even when the active ingredient in the stimulus is removed. For example, if someone received a specific therapeutic medication that triggered a biological response then the active ingredient of that therapeutic medication was removed, the individual would still have a biological response to taking the placebo medication, therefore, experiencing the placebo effect.
 
Neurobiological mechanisms are more complex and can involve feel-good neurotransmitters, metabolic changes in the brain, and other interdependent changes triggering the placebo effect (1,2,3). 
 
Researchers are still working out how these mechanisms work independently and potentially together to achieve these outcomes (1,2).
 
While we cannot say exactly why we may have a placebo response, we know they are real (1,2,3).

Can there be adverse effects to this phenomenon? 

Often, we hear about the placebo effect positively impacting a person's health or wellbeing. There is also a nocebo effect in which an inert substance adversely impacts a person's perception of health or wellbeing. 
 
The nocebo effect is similar to the placebo effect in that an inert substance causes a physical and or psychological response. However, the nocebo effect encompasses unpleasant or adverse responses from the inert substance. 
 
For example, if someone is taking an inert pill they believe will cause an unpleasant physical side effect like nausea, they may report feeling nauseous while taking the pill, even though it's an inert pill that doesn't impact bodily systems.

Does it work outside of a clinical setting?

Yes. Many dietary and herbal substances and products do not provide clinically relevant, measurable health impacts, yet individuals anecdotally report better health and wellness after taking and using the products. 
 
The perceived results can be explained by the placebo effect, especially when it relates to the relief of an ailment such as pain, mild anxiety, and other similar symptoms (1,2).

Am I being fooled?

As we covered, placebo effects are genuine psychobiological events (1,2). This is especially true if a placebo treatment improves our quality of life without any negative side effects or unnecessary medical intervention.  
 
As it relates to medical treatment, it's unethical for medical professionals to mislead patients about their care so a medical doctor will not prescribe inert medications or treatments to patients without first discussing it with them (1,2). 
 
Clinical studies where someone may receive a placebo treatment occur with the full consent of the people participating in the study (1,2). 

Can the placebo effect cure illnesses?

No. While the placebo effect may help us manage pain, anxiety, and other ailments and side effects related to treatments, it will not cure or prevent illness or medical conditions (1). For example, the placebo effect may help us manage arthritis pain, but it will not treat arthritis. 
 
It's important to work with a medical professional to treat medical conditions. 

The good news.

Knowing the powerful connection between our mind and our bodies can help us as we make choices throughout our day. Maybe, a little extra positivity or a new self-care ritual can trigger the placebo effect in our life.