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46 Placebo Effect Statistics: 2019/2020 Data, Examples & Implications

by Arthur Zuckerman

The term placebo may be popularly used when it comes to medicine. However, the placebo effect is also extensively studied and well-documented in human activities, such as sports, cognitive enhancement, and marketing. It’s not only medical researchers that work with and around the placebo effect. Neuromarketers are adept at using the placebo effect to coax target customers into purchasing their products. If you are interested in what areas of human life placebos influence, this placebo effect statistics article is for you.

We’ll not only share interesting statistics but also give you a simplified version of the science behind the placebo effect so far. In this way, you will have a better chance of harnessing it. This is important to the business setting, especially if you are a marketer as marketing actions can shape expectations and, by extension, brand perception. However, if you just want a quick rundown or statistical fact sheet just to gain some fun knowledge about the placebo effect, then you’ve also come to the right place.

Placebo effect statistics

1. The Science of Placebo: In Brief

The word placebo has its roots in Latin. It means “I shall be pleasing.” In medical science, the placebo effect happens when placebos or “sham or inappropriate treatments and medicines” work just because patients believe them to work beforehand. Also, the term nocebo is used for a neutral substance that creates harmful effects. Both effects show that our preconceived notions and attitudes towards things or activities affect actual outcomes and how we perceive them. Prior beliefs have power over posterior outcomes and percepts.

The Roles of Endogenous Opioids

Opioids are known for their pain-relieving or analgesic effects. Also, opioids are native to our bodies. And, scientists have shown that our endogenous opioids play a role in the expectancy-based placebo effect. This involves opioid-rich regions and the periaqueductal gray (PAG), the main control center for pain modulation. The PAG also plays a role in how we respond to threatening stimuli. Curiously, it was also found to play a role in consumption. This could be a hint of the placebo effect in marketing.

  • In one placebo study, researchers found that 8 out of 11 key opioid-rich regions showed positive opioid values and none showed decreases. Of the total 27 brain regions of interests they studied, 14  showed significant placebo-induced increases and none showed decreases.
  • In the same study, the placebo effect magnitudes range from 5% to 17% of the baseline metric they took. This shows a significant increase in opioid activation.

Moreover, researchers think that it isn’t just a person’s expectations and bodily chemicals that can influence therapeutic outcomes. Subjective quality of care and social support also play a role. Thus, the placebo effect is not just caused by siloed internal beliefs. Our beliefs and attitudes are also mediated by such social factors as patients and people, which in general, are embedded in their immediate environments. Thus, social factors play a key role in placebo effects.

Social Factors and Placebo

Scientists study socially-influenced placebo effects using open and hidden treatment administration testing. Open treatments are procedures done with the knowledge of the patient complete with the usual social interactions with medical personnel. Hidden treatments are procedures that are usually done via machine-assisted methods without the knowledge of the patient. For instance, a machine pumping the required dose at the set time in the IV without the patient knowing.

  • Researchers found that an analgesic dose of four painkillers (buprenorphine, tramadol, ketorolac, and metamizole) in a postoperative setting to reduce pain by 50% is higher in hidden infusions than in open infusions.
  • In a study where diazepam is administered to reduce post-surgery anxiety, those with open infusions scored a mean±standard deviation of 37.7±9.5 on the state of anxiety inventory test (STAI-S)  after two hours with the baseline of 49.7±11.3.  That’s a considerable decrease. For the hidden group, they had a baseline average of 51.0±11.9. After two hours of intake, the mean was up slightly to 53.1±10.6. Lower scores mean lower levels of anxiety. This indicates open administration seems to work better.
  • When it comes to open and hidden interruptions of diazepam, the open group scored an average of 48.5±10.5 and 51.8±12.5 after at the 4h and 8h marks respectively. This is against the baseline of 42.4±9.1. Knowing that drug administration was stopped, they reported an increase in their anxieties. For the hidden group, the baseline was 40.2±11.2. This stayed almost the same after four hours at 40.7±10. However, they scored 0.6±10.4 after eight hours. This indicated that a hidden interruption of drug intervention did not induce any anxiety relapse.

Source: Colloca and colleagues

2. Placebo in Medical Trials

The placebo effect is a real and measurable psychobiological phenomenon. It pervades almost everything within the therapeutic context. Thus, when it comes to medical trials, testing against placebos is deemed to be the acid test for the effectiveness of a drug. Randomized clinical trials (RCTs) test against placebos and make use of randomizations and blinding. Thus, researchers can isolate the effects of the tested drugs or treatment.

  • Placebo cure rates range from a low 15% to a high 79%. It doesn’t help that social cues affect placebo analgesia. The placebo effect increases as the length and number of treatments increases. Thus, researchers have to take into account the social factors in delivery procedures.
  • Since 2000, the total number of registered clinical studies worldwide has risen. There were only 2119 registered clinical trials globally back in 2000. Come 2015 it was 205,372. In 2016, there were 233,171 registered. And, there were 262,361 in 2017, 293,341 in 2018, and 318,091 registered as of October 2019.
  • As of May 18, 2020, there were a total of 339,723 studies. Out of these, 50% were located exclusively outside the US while 34% were located exclusively inside. Only 5% of clinical studies are done concurrently inside and outside the US. However, there were 12% with their locations unaccounted for.
  • Of the 339,723 studies, 266,918 or 79% were interventional. Among the four intervention types, drug or biologic intervention has the most count with 148,462. Behavioral or other interventions had 86,823. Surgical procedures numbered at 28,067, and device interventions were 34, 431. It is good to note that many studies have multiple interventions. Thus, the sum of the counts does not equal the total number of studies.

Moreover, patients participating in RCTs don’t usually grasp the meaning of procedures and their justifications. So, there’s an ethical side to the testing. It doesn’t help that many participant-information materials are mostly devoid of placebo justifications and risk explanations.

  • In a set of 52 RCT, only 35% or 18 of the study protocols provided some rationale for placebo use.
  • Only 15 or 29% of the statements, the principal investigator (PI) provided the justification for its use.
  • There were only nine papers or 17% that stated possible risks associated with placebo use. Only six or 12% discussed possible risks associated with placebos.
  • Only 23% or 12 RCTs included an explanation of why a placebo is necessary for sets of participant-information materials.


3. Medical Treatment and Placebos

Now, from a scientific perspective, we know that placebos work, And, the placebo effect may well explain why traditional shamanic cures and therapies are effective. Belief is a powerful thing as it primes our bodies to be conducive to healing. This is why some medical professionals and scientists advocate the harnessing of the placebo effect to make healing better and faster.

Placebo Prescriptions

  • Globally, 17% to 80% of doctors have routinely prescribed placebos. About 29% to 97% of general practitioners (GPs) have used placebos at least once in their career.
  • About 15% to 89% of GPs globally have used placebos monthly while around 1% to 75% use placebos at least weekly.
  • Around 2% to 15% of GPs globally prescribed pure placebos while around 53% to 89% prescribed non-specific therapies or impure placebos. Pure placebos are treatments that contain no active ingredients. Impure placebos are treatments that contain active ingredients but are not recommended for a condition’s treatment.
  • In the UK, researchers found that about 97% of GPs have prescribed placebos.
  • 10% of these GPs have given out pure placebos.
  • Also, the UK survey found that more than 1% of GPs used pure placebos at least once a week. On the other hand, 77% of GPs used impure placebos at least once a week.
  • Most UK doctors believed placebos are ethical in some circumstances. 66% believe this for pure placebos and 84% believe this for impure placebos.

Sham Surgeries

There are also ethical quandaries when it comes to sham treatments, especially those that are invasive. However, when researchers take a look at improvement rates, both subjective and objective, they found that sham surgery “works” in astonishing levels some of the time.

  • In a meta-analysis involving 2902 patients, it was found that the mean improvement for sham groups vis-a-vis active treatment was 78% in pain-related conditions.
  • In the same study, the mean improvement for sham groups for obesity was 71%.
  • Mean improvements of sham surgery for gastroesophageal reflux disorder (GERD) were at 57%, the same as other conditions.
  • However, mean improvements were smaller in classical-surgery trials at 21% than endoscopic trials at 73% and percutaneous procedures at 64%.
  • In a study of 53 sham surgeries, 13 or 25% of the placebo effect studies reported subjective improvements in pain while 32% or 17 reported improvements in function, and 15% reported improvement on the quality of life.
  •  About 42% or 22 out of 53 reported an objective primary outcome. This means that measures did not depend on just patients or assessors.

Subjective Benefits vs Objective Performance

  • In one asthma and placebo study, subjective improvements felt by patients for a real drug (Albuterol) was reported to be 50%. They reported a 45% improvement from a placebo. There was 46% subjective improvement from sham acupuncture and only 21% improvement from no intervention. In this particular case, placebos do only four to five percentage points worse than an actual drug when it comes to subjective improvement. Or, this particular drug is only about four to five percentage points subjectively more therapeutic than placebos.

Source: Ted J. Kaptchuk and colleagues

  • However, in the same study, researchers found that objective results from interventions are far from the perceived ones above. When it comes to the objective Forced Expiratory Volume (FEV) test, patients that took Albuterol exhibited a greater change in FEV with at 20.1%. FEV for patients that took placebo, sham acupuncture, and no-intervention control were at 7.5%, 7.3%, and 7.1% respectively.

Source: Ted J. Kaptchuk and colleagues

Mental Health 

The placebo effect also rears its head on mental disease treatments. As such, it is harder for medical researchers to isolate an intervention and measure its effectiveness. But because of placebo being just around. Many mental health professionals think that it is best to take advantage of it. However, there may be dangers.

  • It was found that significant dopamine release can occur when patients know that there is a 75% probability of them receiving medication but not with all other probabilities (25%, 50%, and 100%). This shows that anticipation of therapeutic benefit, in itself, can elicit this feel-good hormone.
  • In one depression and placebo study, it was found that there was no significant difference in response rate in completers between medicine (53%) and placebo (42.3%). However, those who have experience with antidepressants have greater response rates to medicine at 52.4% than placebo at 25%.
  • Also, it was later found that clinical improvements for people who have previously taken antidepressants were at 45% while clinical improvements for placebos from the same group were only less than 30%.
  • On the other hand, those that have never taken antidepressants prior to the research experienced a little more than 60% clinical improvement using both medicine and placebo

According to these mental health placebo effect statistics, placebos seem to have a greater impact on people that have no experience with real medication. In fact, placebos can have the same level of effectiveness as real medication as per the data. On the other hand, prior experience with medications seems to dampen both the effectiveness of medication and placebo. However, the data shows that patients with experience with antidepressants gain more clinical improvements while on medications than on placebos.

Source: Hunter and colleagues 2015; Irving Kirsch, 2019

4. Sports, Cognitive Enhancements, and Placebos

In the world of sports, victory and defeat are separated by just inches and milliseconds. Thus, athletes take every advantage they could get. Some legally and some illegally. However, placebos and the power of belief seem to play a big part.

  • In a cycling and placebo study, researchers found a likely trivial increase of 1%  in mean power over baselines that have been associated with experimental trials where subjects believed they have ingested caffeine.  This can rise to a likely beneficial 2.2% increase in power.
  • On the other hand, subjects produce 1.4% less power than baseline when they believe they took a placebo.
  • As perceived caffeine intake increases, more power was produced in a 10 km cycling time trial with placebos and conditioning. When participants believed that they took 4.5 milligrams per kilogram of bodyweight (, they produced 1.3% more power over the baseline. They produce 3.1% more power over baseline when they believed they took 9.0 of caffeine. Moreover, all subjects reported caffeine-related symptoms without caffeine intake. When they were told that they were given a placebo and were really given a placebo, the percent change from their baselines had an average of -1.4%.
  • In three studies concerning maximal weighted lifts, two out of three samples were informed that they are receiving anabolic steroids. Instead, they received a placebo. The percent changes from their baselines were 9.6% and 4.6% respectively. On another test, participants were informed that they are taking amino acids. Instead, they were given placebos. Their maximum weights lifted averaged 11% over their baselines.
  • In a study with 44 university students with a leg extension task for a performance measure, researchers informed them they would be taking caffeine to help them with their performances. Instead, they were given placebos. Researchers found 11.4% changed when they were given placebo alone and 25.9% change when done with placebo and conditioning.
  • Researchers found that informing participants that they are using an enhanced tennis racket, they improve on their tennis serves by 5% even if the racket was only a placebo.
  • In a standing long jump performance test, sub-elite athletes that used kinesiology tape only registered a 1%  change in performance. Those that got a placebo registered a similarly little 1.5% improvement.

Source: Beedie and colleagues

Cognitive Enhancement

Just like athletes, tech entrepreneurs, coders, and even serious academics are embedded in highly-competitive environments. Thus, they also want to get an edge over the competition. One way they do this is by ingesting cognitive enhancers like modafinil and racetams. Stimulants are popular in these circles.

  • Non-medical lifetime stimulant use is popular among US college students. 8.3% claim a lifetime use of them and another 5.9% use it in the last year. Moreover, only 4.3% of the German population and 6.5% among Australian university students have a lifetime non-medical use of stimulants.
  • In one study, administered amphetamine salts enhanced the cognitive performance in only 2 of 31 subtests of a neuropsychological test battery. However, the expected administration of the medication itself yielded both actual and perceived cognitive performance regardless of ingesting mixed amphetamine salts or a placebo.
  • Even in creative thinking, placebos can help bring out higher originality. The placebo group for a Creative Foraging Game (CFG) task had a median score of 7.0 with a ±0.5 standard deviation. The control group’s got 6.7±0.4.

Researchers found that cognitive enhancement drugs or “smart drugs” may affect the perception of cognitive enhancement. They may also help in wakefulness and focus. However, cognitive enhancement is a totally different animal. And, placebos work with active ingredients to help contribute to both actual and perceived benefits.

5. The Placebo Effect in Marketing

It has long been known by cognitive scientists and behavioral economists that marketing actions can lead to placebo effects. One of such marketing action is pricing strategy. More times than less, products priced lower feel more inferior than those priced higher. Prices act as an external cue that builds up an expectation in people about how good or bad the product is. They build expectancy. What’s more, even discounts play a huge role.

Expectancy, Price, and Discounts

An experiment involving a commercial drink that is advertised to increase mental acuity on its package, it was found that participants in a puzzle task who believed that they were charged with a reduced price performed worse than those who believed to have been charged with the actual price. The participants weren’t really made to pay. This was also done to induce a placebo effect. Moreover, in the study, participants were separated into two groups, low expectancy or high expectancy. High expectancy participants were asked the question of how much they expect the drink to improve their concentration and performance.  The low expectancy group was not.

  • The low expectancy group that “paid” the full price of the drink had a mean of solving 9.5 out of 15 puzzles in 30 minutes while the those in the same low expectancy group that “paid” the reduced price had an average of solving 7.7. The puzzles solved in the control condition had an average of 9.1.
  • In the high expectancy group, those that paid full price have an average score of 9.9 while those in the reduced-price group have an average score of 5.8. Interestingly enough, during debriefing, all participants denied that the price of the drink affected their performance.

However, in a modified experiment where one group was informed of the price-efficacy relationship and the other was not, the placebo effect was dampened to a degree. Those that were informed of the price-efficacy link are part of the high price-efficacy salience group while those that were not part of the low price-efficacy salience group.

  • The high price-efficacy salience group scored differently than the first experiment. The full-price group averaged 8.0 out of 15 puzzles in 30 minutes and the discounted-price group averaged an 8.2. It seems the knowledge of price-efficacy link diminished placebo effects. The number of puzzles solved in the control condition was 8.0.
  • Also, the low price-efficacy salience group scored differently. Those in the low price-efficacy salience group that paid the full price averaged 8.3 solved puzzles and those that paid the discounted price scored a 6.8.

Source: Ariely and Colleagues

Working With and Around the Placebo Effect?

The placebo effect examples, experiments, and statistics above show that the placebo effect is ubiquitous in the everyday human experience. It is in competitive ventures from sports to academia to tech. It plays a large role in business and consumerism. Moreover, some are convinced that knowing more about the placebo effect can help us dampen it a bit and harness it when we need to.

For instance, in the medical field, many argue that professionals should harness the placebo effect more. Remember, the placebo effect is not just induced by a sugar pill or sham treatments. It is also induced by positive social interactions. So, acting courteously and humanely towards patients can induce actual and perceived healing.

Moreover, on the business side of things, maybe wisening up to marketing placebo effects can help the market generate better-priced and better-quality products and services. To wit, the wisening up to the placebo effect may already have been a big part of how products and services get selected out of markets all the time. Maybe, our unconscious has more to do with it than our conscious just like the placebo effect statistics above indicate.

Lastly, the placebo effect is well-studied. What’s more, from these studies, one thing looks to be sure: the placebo effect won’t go away. It can have positive and negative effects. Thus, we can either live with it or learn to work with and around it. However, it’s hard to say if we really have a clear choice in the matter.



  1. Placebo Effects of Marketing Actions: Consumer May Get What They Pay For
  2. Placebo effects on human μ-opioid activity during pain
  3. Overt versus covert treatment for pain, anxiety, and Parkinson’s disease
  4. Placebo-controlled clinical trials: how trial documents justify the use of randomization and placebo
  5. The Placebo Effect: How It Works
  6. Active Albuterol or Placebo, Sham Acupuncture, or No Intervention in Asthma
  7. Trends, Charts, and Maps
  8. Survey finds 97% of GPs prescribe placebos
  9. How often do general practitioners use placebos and non-specific interventions? Systematic review and meta-analysis of surveys
  10. Efficacy of a Non Blind Placebo Prescription
  11. To what extent are surgery and invasive procedures effective beyond a placebo response? A systematic review with meta-analysis of randomised, sham controlled trials
  12. Use of placebo controls in the evaluation of surgery: systematic review
  13. Impact of Antidepressant Treatment History on Clinical Outcomes in Placebo and Medication Treatment of Major Depression
  14. Antidepressant Treatment History and Drug-Placebo Separation in a Placebo-Controlled Trial in Major Depressive Disorder
  15. Placebo can enhance creativity
  16. Anabolic steroids: the physiological effects of placebos
  17. Expectancy Effects and Strength Training: Do Steroids Make a Difference?
  18. Placebo Effects of Caffeine on Cycling Performance
  19. The Effect of Placebo-Induced Changes in Expectancies on Maximal Force Production in College Students
  20. The top-down influence of ergogenic placebos on muscle work and fatigue
  21. Motor imagery and ‘placebo-racket effects’ in tennis serve performance
  22. Kinesiology tape does not promote vertical jumping performance: a deceptive crossover trial
  23. Individual Differences in Marketing Placebo Effects: Evidence from Brain Imaging and Behavioral Experiments
  24. Placebo Effects of Marketing Actions: Consumers May Get What They Pay For

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