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Not just smoke and mirrors: placebo’s place in modern medicine

Belief is a powerful medicine but the term “placebo” has negative connotations. In modern evidence-based medicine, treatments considered worthless are described as no better than placebos. But this description…

Despite placebos’ reputation as worthless therapy, many medical practitioners still use them. FML/Wikimedia Commons

Belief is a powerful medicine but the term “placebo” has negative connotations. In modern evidence-based medicine, treatments considered worthless are described as no better than placebos. But this description belies the real picture.

Placebos are characterised as inert, in contrast to active drugs or other treatments. Yet some argue that there’s a role for placebo interventions in mainstream medicine.

Professor Fabrizio Benedetti, a physician and neurophysiologist from the University of Turin Medical School and National Institute of Neuroscience in Italy, has devoted much of his career to the study of placebo effects. He argues that there’s not a single placebo effect but many. These are based on different mechanisms and occur in different medical conditions and therapeutic interventions.

A placebo effect can be caused by an expectation, and the expectation of relief from pain can reduce anxiety. Expectation can also activate a reward mechanism in the nucleus accumbens and release dopamine. The nucleus accumbens is the region in the brain thought to play an important role in reward and pleasure. In this case, the reward is the treatment itself, that is, the reward is the expectation that in a few minutes you will feel better.

A placebo effect can also be produced through learning. If a particular drug has produced positive effects in the past, replacement with a placebo without the patient’s knowledge is likely to produce a similar effect as the active drug.

Placebo responses can be subconscious, and these are mostly created through classical conditioning. Aspirin, for instance, relieves pain and aspirin tablets usually are white and round. If a person has had experiences of pain relief after taking an aspirin, then any tablet that is white and round could have an analgesic effect. Conditioned placebo responses also work for animals.


A placebo’s effectiveness also depends on its type. Placebo injections appear to be more effective than pills. Very small and large pills are more effective than medium-sized pills. Even the colour of a tablet has an influence. Expensive placebos work better than low-priced ones.

Placebo responses also depend, in part, on the condition being treated. Placebos don’t appear to affect diabetes, for instance, while strong placebo effects can be observed for pain.

Clinical trials are not a good way to study placebo effects, says Professor Benedetti. A placebo effect is a psychobiological phenomenon, expressed in brain activity. To understand what’s going on in the brain when a placebo is given, the person has to be studied in the laboratory.

For this, Professor Benedetti uses a “balanced placebo design” involving four groups. The first group receives a placebo, but is told it’s the active drug. The second group of patients receives a placebo and is told it’s a placebo. The third group receives the active treatment and is told it’s a placebo, while the fourth group receives the active treatment and is told the truth.

Using this and other methods, Professor Benedetti found psychobiological placebo effects not only for pain, but also for the immune system, the endocrine system, the cardiovascular system and Parkinson’s disease. These are unconscious placebo effects based on classical conditioning.

And despite placebos’ reputation as worthless therapy, medical practitioners still use them. A survey of US internists and rheumatologists found that more than half had used placebo treatment in the previous year. In Canada, a survey of physicians and psychiatrists found that one in four prescribed placebos regularly as part of routine clinical practice.


The German Medical Association (Bundesärztekammer, BÄK) recently recommended that placebo treatments be used in certain circumstances. The BÄK reminded its members that the placebo effect occurs in all treatment situations and its extent depends on the quality of the doctor-patient relationship. The organisation called for doctors to improve their knowledge of placebo research and use placebos to maximise desirable drug effects, minimise undesirable effects, prevent adverse drug reactions, and use the financial resources of the health system in a more efficient way.

But how can placebo treatments be used ethically and without deception?

The BÄK advised its members that placebo treatments outside of clinical trials are ethically justified in the following circumstances:

  • if there is no current proven (drug) intervention for that particular medical condition;

  • for minor conditions in circumstances where the patient expresses a wish for treatment; and

  • if it seems likely that a placebo treatment will be successful.

Good communication is essential and the patient should be informed of potential benefits and harms of the placebo treatment. The BÄK is now calling for internationally recognised guidelines on the use of placebo treatments.

In the absence of a consensus and international guidelines, Professor Benedetti has this advice about the ritual of the therapeutic act:

“I would say that the take-home message for clinicians, for physicians, for all health professionals is that their words, behaviors, attitudes are very important, and move a lot of molecules in the patient’s brain.”

So a placebo can be more than just a placebo, and mainstream medicine would do well to use its potential for the benefit of patients and the health system.

Join the conversation

12 Comments sorted by

  1. Sam Chafe

    Retired scientist

    The author hails the benefits of placebos but the fact remains that such prescription is a deception. Although seemingly beneficial in some instances, mainly for minor problems, the possibilities for duping believing individuals to their detriment is very real: witness the extremes of faith healing and the charlatan remedies for incurable cancer. The author notes that placebos do not work for diabetes, something quite unsurprising as no amount of belief can induce a damaged pancreas to start producing insulin.

    Amongst believers, religion works the same way as placebos: if one is convinced in their belief, nothing will shake their commitment. An interesting trial would be to test the efficacy of placebos on believers versus non-believers, or whether placebos worked for those committed to 'objectivity', scientists, for example.

    1. Graham Gower

      ex engineer, evol biology student

      In reply to Sam Chafe

      Is there a way to tell someone they are getting a placebo without reducing its effectiveness?

      E.g. I understand that a placebo can be effective, therefore giving me one should placate me to the belief that it will work.

    2. Paul Richards

      logged in via Twitter

      In reply to Sam Chafe

      Sam - testing individuals value system and quantifying it sounds very draconian. Will the data be made available through worlds intelligence conduits?

      Point taken though.

    3. Monika Merkes

      Honorary Associate, Australian Institute for Primary Care & Ageing at La Trobe University

      In reply to Sam Chafe

      Hi Sam
      Placebos without deception (i.e. the patient is told that they receive a placebo) can be effective, as demonstrated in this randomised controlled trial:
      The study is also reported here:
      However, this is only one study, and as is so often the case, more research is needed to confirm (or refute) the findings of Kaptchuk and colleagues, and to explore for which patients/conditions/context etc. placebos without deception are effective.

  2. Sam Chafe

    Retired scientist

    Unfortunately, telling someone that a placebo would work is a contradiction in terms. If someone knows that placebos are, well, placebos, they know they don't work. Hence, they won't.

    1. Graham Gower

      ex engineer, evol biology student

      In reply to Sam Chafe

      But placebos *do* work. And I know this.

  3. Sam Chafe

    Retired scientist

    In which case they are not placebos because a placebo is something you provide as a neutral substitute for an active medication. If you believe that anything you substitute, say water for morphine, to cure a migraine, you don't need a placebo, or morphine; all you need to do is say I'm going to stop having a migraine and, presto, you are cured. Good luck with that, and if you work out a method, let me know.

  4. Grendelus Malleolus

    Senior Nerd

    My understanding of the placebo mechanism is that there can be relief from symptoms but no change to the underlying condition - about what you would expect where there is not an actual active ingredient but when the person feels better about having at least seen someone about their ailments.

    As for the guideline that a placebo can be used "if it seems likely that a placebo treatment will be successful" then that really muddies the waters - it seems to me that it is not that the placebo is successful, just that the person got better normally, but with the placebo removing some of the distractions of being ill.

    1. Paul Richards

      integral operating system

      In reply to Grendelus Malleolus

      " .... really muddies the waters" - Grendals

      Yes it does. That is the issue, the input into human mind is a very powerful thing, controlling hormones that flood the brain, body and organs sending signals about homeostasis that is still challenging science. The responses are real.

      The actual effect is more than just "in the mind" or a "distraction" it is physiological, measurable when bloods are taken and the bodies electrical responses are measured.

      Any challenge to the efficacy of cause or effect needs to be considered at the highest level of human thought.

  5. Gillian Maguire


    The Wikipedia article on placebo response was one of the most interesting things I have read for years.

    The article by Steve Silberman in Wired "Placebos are Getting More Effective: Drug Companies Don't Know Why?" provides a different insight into the placebo problem identified in the recent Marcia Angell broohaha in the New York Times.

    I'm not a scientist and have written about it at

    If I have got it wrong let me know.