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The ethics of placebo treatments in clinical practice: a reply to Glackin
  1. Anne Barnhill1,
  2. Franklin G Miller2
  1. 1Department of Medical Ethics and Health Policy, University of Pennsylvania, Philadelphia, PA, USA
  2. 2Weill Cornell Medical College, New York, NY, USA
  1. Correspondence to Dr Anne Barnhill, Department of Medical Ethics and Health Policy, University of Pennsylvania, Philadelphia, PA 19104, USA; anne.barnhill{at}


In ‘Placebo treatments, informed consent, and “the grip of a false picture”’ Shane Nicholas Glackin argues that if a physician offers a patient an inert placebo with the following disclosure, this is compatible with informed consent and is not deceptive: ‘I would like to offer you a pill which I believe can help lessen your suffering. I do not know exactly how it works. I have other pills to offer whose mechanism is clearer, but I am not sure that they will work better for you, and they may also entail more serious side effects’. According to Glackin, telling patients that the recommended treatment is an inert placebo is providing incidental information, analogous to telling a patient the chemical details of an active drug. He argues that this information would influence a patient's decision only if she was ‘in the grip of a false picture’ that inert drugs do not have physical effects on patients’ bodies. We contend that this disclosure typically is incompatible with informed consent and typically is deceptive. We give an example of a transparent placebo disclosure, that is, a disclosure that is compatible with informed consent and is not deceptive.

  • Informed Consent
  • Autonomy
  • Clinical Ethics
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Recently, bioethicists have engaged in considerable discussion and debate about the ethics of clinicians recommending placebo treatments to their patients.1–5 In ‘Placebo treatments, informed consent and “the grip of a false picture,”’ Shane Nicholas Glackin enters the fray with an ethical argument in favour of undisclosed use of placebos.3 He argues that undisclosed placebo use does not preclude informed consent and does not deceive the patient, two of the main ethical objections to the practice.

While the range of ‘placebo treatments’ has not been clearly defined and is contested, Glackin focuses on the use of inert placebos—that is, placebo pills lacking any medication in them—recommended or prescribed to promote therapeutic benefit by means of generating a placebo response. In discussing the ethics of placebo use, Glackin argues that the following disclosure to a patient by a physician would be acceptable: ‘I would like to offer you a pill which I believe can help lessen your suffering. I do not know exactly how it works. I have other pills to offer whose mechanism is clearer, but I am not sure that they will work better for you, and they may also entail more serious side effects’. For the sake of our critique, we will call this ‘non-transparent placebo disclosure’.

This disclosure notably leaves out the information that a treatment is a placebo. Glackin argues that omitting this information does not prevent the patient from giving informed consent and it is not deceptive. In this commentary, we critique both of these claims. The critique paves the way for suggesting a disclosure regarding placebo treatments that is not deceptive and is compatible with informed consent.

Does informed consent requiring disclosing that a treatment is a placebo?

The central argument of Glackin's paper is that for a patient to give informed consent to a placebo treatment, she need not be informed by the physician that it is a placebo. Whether informed consent requires knowing that a treatment is a placebo is a central question in the ethics of clinical use of placebos, and one that we have explored in previous work.3 ,6 ,7 The answer to this question depends upon both one's theory of informed consent and the attitudes of patients towards placebos.

Following the influential analysis of informed consent of Faden and Beauchamp, Glackin takes informed consent to require that the patient has ‘substantial understanding’ of a treatment recommended by a physician. He argues that the information that a treatment is a placebo is not required for patients to have a substantial understanding of the treatment: ‘that the treatment is pharmacologically inert is a merely incidental part of what the patient is asked to consent to, at a level of causal detail far beyond what she standardly needs to understand her decision’. Glackin points out, rightly, that not all information about a treatment is required for the purposes of informed consent. For example, doctors routinely ‘do not tell patients the biochemical details of how and why their treatments work’. Doctors need not tell patients that a drug works by mechanism X rather than by mechanism Y, as this is not the sort of information that patients normally need in order to understand and authorise a recommended treatment.

According to Glackin, the fact that clinicians can legitimately omit any information about the mechanism of action of the drugs they prescribe has important implications for what informed consent requires in the case of inert placebo treatments. He argues that once we recognise that inert placebos act on the brain, just as active drugs act on the brain, we will see that the distinction between taking a placebo and taking an active drug is insignificant. Those who think that there is a significant distinction between inert placebos and active drugs are in the grip of a false view:The placebo does not act on the body, on this view, but merely ‘fools’ the mind into believing that the body has been treated, thereby causing it to trigger or accelerate the body's own supplementary healing mechanisms. This dichotomy, between acting on the patient's body and ‘merely’ acting on his or her psyche, is an intuitively appealing one. However, it results from what, following Wittgenstein, we may term a false picture of the mind–body relation. What it presumes is that there is a total causal separation between the mind and body, such that acting on the mind is not thereby also acting on the body. Call this picture ‘naïve Cartesianism’…

Glackin assumes that the only reason why it would be substantial information that a treatment is inert is if a patient incorrectly assumes that inert substances act ‘merely on the mind’, whereas active drugs act ‘on the body.’ If a patient understands that inert substances can act ‘on the body’, then it is not substantial information that the treatment is an inert substance. Glackin assumes that since the outcome of taking an effective placebo and the outcome of taking an effective active drug are the same—the body/brain is changed in a way that corresponds to symptom relief—any remaining differences between the placebo and the drug are not relevant.

Of course, there is a difference between a placebo and a drug that's indicated for the patient's condition, even when they both ultimately cause the same outcome (ie, they both change the body/brain in a way that corresponds to symptom relief). The difference is that placebos achieve symptom relief through a different process than active drugs. For example, consider the case of placebo pills given for pain versus analgesics. Analgesics achieve pain relief through a pharmacological-physiological pathway: for example, analgesic drugs are taken by mouth and enter the blood stream, whereby they produce analgesic effects in the brain. In contrast, placebos achieve pain relief through a psychological-cum-physiological pathway. One way in which placebo treatments are effective is that they tap an expectation pathway by means of a ‘top–down’ process in the brain. They work via the patient's belief that she is taking an effective treatment. Though they have the same outcome, placebo pills and analgesics achieve this outcome through different causal pathways. Is this difference in causal pathways between placebos and non-placebos a piece of ‘substantial information’? That is, does informed consent require that patients be told that a treatment achieves pain relief through a ‘top–down’ placebo causal pathway rather than through the standard pharmacological–physiological causal pathway?

In our view, informed consent does require that patients have this information, and this is because reasonable patients would want this information. We accept a view of informed consent according to which informed consent requires giving patients all the information that reasonable patients would want to be given, and we assume that reasonable patients would want to be informed about whether a treatment is a placebo (in ‘do patients want to know that treatments are placebos?’, we provide empirical evidence in support of this assumption). Patients expect that the pills they are prescribed contain medication with therapeutic properties—that is, that the pills work by some sort of pharmacological–physiological process. While they may not care what the exact mechanism of action of the pill is, it is reasonable to assume that they will care about whether they are being given a drug with chemical properties that have a direct effect on their condition/symptoms or, instead, being given a placebo that works through a psychological-cum-physiological process.

Glackin's view is that informed consent does not require being told that a treatment achieves pain relief through a ‘top-down’ placebo causal pathway rather than through an pharmacological-physiological causal pathway. Regarding the non-transparent placebo disclosure, Glackin writes ‘The suggested locutions are therefore perfectly accurate; the treatment is known to relieve symptoms, and we are not really sure why, or what the causal pathways are. This is the basic information which the patient requires to make an informed decision’.3

Glackin asserts that informed consent requires ‘substantial information’, but does not define what counts as ‘substantial’ information. However, there are textual hints: ‘the idea that the patient would have chosen differently if told the treatment was pharmacologically inert depends on the assumption that the patient is himself or herself in the grip of that [false] picture’.3 And ‘One possible answer [why placebos are different than conventional prescriptions] might be that we have reason to think the patient will not consent if informed the treatment is a placebo’.3

These passages, as well as Glackin's overall argument, suggest that he accepts a view of informed consent according to which physicians must provide information only if this information would likely affect a reasonable patient's choice of treatment. On this view, even if patients would wish to have certain information, informed consent does not require disclosing this information unless it would likely affect a reasonable patient's choices. On this interpretation of Glackin's argument, he is assuming that it would not affect a reasonable patient's choice of treatment to learn that a treatment is a placebo because placebos work ‘on the body’ just like active treatments. The only reason why a patient would change his mind about taking a placebo treatment is if he falsely believes that inert treatments work ‘merely in the mind’ and not also ‘on the body.’ We agree that a reasonable patient should not change her mind about taking a treatment just because it is a placebo treatment, all other things equal. But we think that a reasonable patient might nonetheless want to know what she is putting into her body, and in particular whether it is a placebo or not (even if the reasonable patient would go ahead and ingest the placebo).

Thus, Glackin's argument also requires accepting the (not uncontroversial) view that informed consent does not require giving patients all the information that reasonable patients would want to have nor does it require giving patients all the information that would actually affect their decisions, but only requires giving them information that should change reasonable patients’ decisions.

An alternate way to argue that undisclosed placebos are compatible with informed consent is to maintain that informed consent requires disclosing all information that reasonable patients would want to have, but then to argue, contra our view, that reasonable patients would not want to know that a treatment is a placebo. While some patients may reasonably wish to remain in the dark about whether a treatment is a placebo, it is doubtful that reasonable patients in general would not want to know that a treatment is a placebo.

Do patients want to know that treatments are placebos?

What would a reasonable patient want to know about a placebo treatment that is being offered to her? One way to surmise what the reasonable patient would want to know is to survey patients. In a study by Chen and Johnson8 in New Zealand, a majority of patients judged that doctors should provide undisclosed placebos in a variety of situations, though many patients thought that undisclosed placebos should be ‘a last option’ or only used ‘on rare occasions’. Lynöe et al,9 in a study of Swedish patients, found that 25% of patients agreed ‘completely’ or ‘for the most part’ that physicians should give placebos more often. They also found that 63% of patients agreed ‘completely’ or ‘for the most part’ that it is acceptable to give a dying patient a placebo and tell her it is a cancer treatment, assuming that there is only a small chance she would discover the truth.

In a survey of 853 US patients, Hull et al10 asked respondents a series of questions about ‘placebo treatments’, defined as follows: ‘A patient experiences a placebo effect when they get better after taking a treatment, not because of the treatment itself, but because the patient expects they will benefit from the treatment. For the rest of this survey, we will ask you to assume that a placebo treatment is a treatment that only works because it can produce a placebo effect. Placebo treatments can be sugar pills or other treatments used to create a placebo effect’. One question probed whether it is acceptable for doctors to recommend a placebo treatment described as ‘a real medicine’. Half of the respondents agreed and half disagreed.10 This suggests that half of the surveyed patients would not endorse the use of placebo treatments when they are not described transparently.

Does undisclosed placebo use deceive the patient?

Glackin asserts that omitting to inform patients that a recommended pill is a placebo—that is, it contains no medication in it—does not deceive patients. He does not give a separate argument for this conclusion beyond his argument that the non-transparent placebo disclosure is consistent with informed consent. But whether this disclosure is consistent with informed consent is a distinct issue from whether it is deceptive. Even if we agreed with Glackin that patients can give informed consent to an undisclosed placebo, the concern remains that his recommended disclosure deceives patients, because it intentionally cause patients to form the false belief that they are receiving a non-placebo treatment.

Consider once again the non-transparent placebo disclosure that Glackin endorses: ‘I would like to offer you a pill which I believe can help lessen your suffering. I do not know exactly how it works. I have other pills to offer whose mechanism is clearer, but I am not sure that they will work better for you, and they may also entail more serious side effects’. We maintain that giving patients placebos with this disclosure is typically deceptive. Typically, a physician would make a disclosure like this because she intends for the patient to conclude, incorrectly, that he is receiving an active drug. Deception is intentionally causing someone to have a false belief that the deceiver believes to be false.11 One form of deception is lying—saying something that you believe to be false, with the intention of getting to listener to believe that it is true.12 But there are other ways of deceiving someone besides lying to her, such as making vague statements with the intention of causing someone to have false beliefs or withholding information with the intention of making someone have false beliefs. In the case at hand, the physician withholds information with the intention that the patient forms a false belief; the physician thereby deceives the patient.

It is reasonable to presume that patients given such a disclosure will form the false belief that they are receiving active drugs, given their background expectations. In clinical settings, patients have the reasonable expectation that the pills prescribed by physicians contain medication with known effective properties for treating the patient's condition. That is what doctors are expected to be doing in making prescriptions. As a result, a vague disclosure that does not explicitly contradict these expectations is likely to confirm these expectations and cause patients to conclude that they are being given active drugs. It is possible that some patients will have different expectations, for example, if their physicians have indicated that they are open to using placebos, but this is not the typical situation.

This conclusion is all the more plausible, once we fill in the details of how placebos will be used in contemporary medical practice. Physicians typically will not write a prescription for an ‘inert’ placebo pill that will be sold to the patient in a pharmacy; rather, the physician will give the patient a bottle of pills. This is not a usual practice; however, sometimes physicians may give patients drugs that they have obtained from pharmaceutical representatives as free samples. Physicians might obtain placebo pills and give them to patients with instructions on how they are to be taken. If so, the bottle of pills will need to be labelled in some way. It likely will not be labelled ‘placebo’ or ‘obecalp’. Instead, the pills are likely to be given a name that sounds like that of a drug to which the placebo treatment is physiologically comparable. In this context, doctors are not offering an unlabelled treatment with a vague disclosure. Rather, they are giving the patient a pseudomedication presented as a medication. It is natural to suppose that most patients receiving such a bottle of pills to take, say, to relieve pain will (falsely) conclude that the pills contain a medication that is pharmacologically active against pain. In other words, recommending placebo treatments in clinical practice without describing them as placebos is likely to deceive by withholding information and by actively communicating false information.

Thus, Glackin's recommended non-transparent placebo disclosure is deceptive; we disagree with his assertion that it is not. In response to this critique, perhaps Glackin could concede that they are deceptive but argue that the alternative to these deceptive disclosures is a full disclosure that also misleads the patient and has the undesirable result of steering her away from an effective placebo treatment. The deception, in this case, could be seen as the lesser of two evils.i In support of his recommended disclosures, Glackin writesThe suggested locutions are therefore perfectly accurate; the treatment is known to relieve symptoms, and we are not really sure why, or what the causal pathways are. This is the basic information which the patient requires to make an informed decision and given the prevalence of belief in the naïve Cartesian picture, further information is not only superfluous, but is apt to actively misinform the patient as to the nature and effect of the treatment.3

Glackin thinks that informing patients that a treatment is a placebo will cause patients to form a false belief about the treatment (ie, the belief that the treatment works only on the mind and not on the body, and thus is not effective). While we disagree with this, what follows about disclosure to patients regarding placebo treatments if it were true? If a transparent disclosure about placebo treatment will necessarily (or typically) mislead patients in the way Glackin suggests, the physician must choose between, on the one hand, giving full information and thereby knowingly causing patients to form the false belief that the placebo treatment is ineffective (and consequently causing patients to refuse a beneficial treatment) and, on the other hand, giving a vague disclosure and thereby intentionally causing patients to form the false belief that the placebo treatment is a drug (and consequently causing patients to accept a beneficial treatment that they would otherwise refuse).

In both cases, the patient ends up harbouring a false belief as a result of the physician's disclosure; shouldn't the physician therefore choose the misleading disclosure that ends up benefiting the patient more? Isn't this the lesser of two evils? No. When the physician intentionally causes the patient to form false beliefs, this is an act of deception, but knowingly causing patients to form false beliefs is not. Physicians have stricter ethical responsibilities to avoid deceiving patients than they do to avoid knowingly but unintentionally misleading patients. This is not to say that it is ethically unproblematic to knowingly but unintentionally cause patients to form false beliefs; physicians should endeavour, when feasible, to avoid this. If a physician can feasibly communicate in an honest way that prevents a patient from forming false beliefs—for example, using different words—then the physician should do so. When a patient falsely concludes that an effective treatment is ineffective and rejects the treatment for that reason, the physician should endeavour to correct the patient's false beliefs; and this is true whether or not the patient's false belief resulted from the physician's communication. Thus, physicians do have ethical responsibilities to communicate clearly and effectively, to avoid unintentionally misleading patients, and to try to correct patients’ false beliefs in at least some cases. But physicians’ means of preempting or correcting patients’ false beliefs should not be to intentionally instil other false beliefs in their stead (except, perhaps, in the most extreme circumstances when the patient's false beliefs will cause him serious harm). The placebo scenarios under discussion are not examples of such cases, as the potential medical benefit to the patient of taking placebos is relatively modest.

Transparent placebo disclosures

The disclosures recommended by Glackin are deceptive and incompatible with patients giving informed consent, given the expectations that patients typically have. There are circumstances in which these disclosures could be compatible with informed consent. For example, if a physician and patient have previously agreed that the physician may offer placebos without explicitly identifying them as placebos, then a disclosure like the one Glackin endorses would be compatible with informed consent. Additionally, there could be circumstances in which it is ethically acceptable to deceive patients, if they have given their prior consent to be deceived. But absent such agreements or conversations about placebo use, this disclosure is deceptive and incompatible with informed consent.

Some placebo proponents have argued that non-transparent use of placebos is unnecessary, as placebos can be given openly and still achieve a therapeutic placebo effect. In a study of irritable bowel syndrome patients, Kaptchuk et al13 found that patients who were given placebo pills with the disclosure ‘placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in irritable bowel syndrome symptoms through mind-body self-healing processes’ showed significantly more improvement than control patients given no pills. This study suggests that open use of placebos can produce a therapeutic effect; of course, it still might be true that non-disclosed use of placebos is more effective.1 ,4

The trick is to have a placebo disclosure that communicates the information that a treatment is a placebo, while presenting and contextualising this information in a way that does not undermine a therapeutic placebo effect. As an example of a transparent placebo disclosure, we recommend the following:Doctor D, a family practice physician, keeps a supply of placebo pills to give to patients when she thinks it could be an appropriate treatment. Patient P visits D for a routine examination. When D ask P to describe how her life is going, P indicates that she has been feeling depressed over the past 2 months. After exploring with P her depressive symptoms and her thoughts about why she is feeling depressed, D says, ‘I'm concerned about your being depressed and would like to work with you to help you get better. I could prescribe you a medication to treat depression, but these drugs have side effects and they don't help everyone. Instead, I am giving you a bottle of pills to take every day for a month. They don't have any medication in them, so you might wonder or be surprised why I would recommend taking them. However, some interesting studies have shown that patients who take placebo pills for various symptoms get better after taking them. We don't know why this happens, but one reason may be what's known as ‘the placebo response.’ Taking pills, even when they have no medication in them, might stimulate your brain's own resources for healing. Try taking one pill each night before you go to bed. I want you to come back for a visit in one month, but call me before then if your depression gets worse. At that time we can discuss how you are doing, and if you are not feeling substantially better, then I can prescribe an antidepressant drug. Also, I encourage you to exercise regularly; that's not only good for your physical well-being but your mental health’.

This placebo disclosure is not deceptive and is compatible with informed consent. Furthermore, this disclosure emphasises that placebos have been shown to be effective; it thus steers patients away from forming the false belief, of concern to Glackin, that placebos work only ‘on the mind’ and are not effective.

Though this disclosure is non-deceptive and compatible with informed consent, a further issue remains. For it to be ethical for physicians to offer placebos with this disclosure, it must have the potential to promote a therapeutic response. Will it? This is an empirical question that would be worth investigating.


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  • Contributors Both authors contributed to conceiving of, writing and editing this manuscript.

  • Competing interests None declared.

  • Disclaimer FGM was an employee of the National Institutes of Health when this article was written. The opinions expressed are the views of the authors and do not necessarily reflect the policy of the National Institutes of Health, the Public Health Service, or the US Department of Health and Human Services.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • i Thank you to an anonymous reviewer for suggesting this.

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