One of the problems scientists have in evaluating the placebo effect is the distinction that can be drawn between ‘true’ and ‘perceived’ placebo effects, where a ‘perceived’ effect might not not be directly attributable to the administration of a placebo. But they also acknowledge the general ignorance of definition and description when it comes to the ‘true’ placebo effect.’A review of the literature shows that most authors confuse the perceived placebo effect with the true placebo effect. The true placebo effect is highly variable, depending on several factors that are not fully understood.’

Ref. E. Ernst, K. L. Resch, Concept of true and perceived placebo effects, British Medical Journal, 1995;311:551-553

A few – just a few – medical professionals bring up the ethics of therapists actually prescribing placebos as an element of treatment.

Margaret Talbot proposes in the New York Times Magazine (1/09/2000):"The truth is that the placebo effect is huge — anywhere between 35 and 75 percent of patients benefit from taking a dummy pill in studies of new drugs — so huge, in fact, that it should probably be put to conscious use in clinical practice, even if we do not entirely understand how it works."

Others might balk at the suggestion, but there seems to be an ethical shadow-line, where a drug-focused therapy may overlap with the physician’s responsibility (duty?) to care for his or her patient as more than a machine, as a being of heart-mind."The placebo effect can occur," as the physician Herbert Spiegel once put it, "when conditions are optimal for hope, faith, trust and love." It might sound sentimental, but then sentiment, working hand in hand with science, can make medical practice so much more powerful. A world in which placebo — preferably in the form of deft encouragement, but sometimes in the form of a harmless pill — was tolerated, even embraced, would be a world in which doctors never forgot that medical practice consists not only of the technologies of diagnosis and treatment but also of the careful tending of a patient’s expectations and the unabashed willingness to comfort."

Margaret Talbot, The Placebo Prescription, New York Times Magazine

Even the skeptics (American English for ‘sceptics’) can’t come down *too* hard on placebos:

"A person’s beliefs and hopes about a treatment, combined with their suggestibility, may have a significant biochemical effect. Sensory experience and thoughts can affect neurochemistry. The body’s neurochemical system affects and is affected by other biochemical systems, including the hormonal and immune systems. Thus, it is consistent with current knowledge that a person’s hopeful attitude and beliefs may be very important to their physical well-being and recovery from injury or illness.
However, it may be that much of the placebo effect is not a matter of mind over molecules, but of mind over behavior. A part of the behavior of a "sick" person is learned. So is part of the behavior of a person in pain. In short, there is a certain amount of role-playing by ill or hurt people. Role-playing is not the same as faking or malingering. The behavior of sick or injured persons is socially and culturally based to some extent. The placebo effect may be a measurement of changed behavior affected by a belief in the treatment. The changed behavior includes a change in attitude, in what one says about how one feels, and how one acts. It may also affect one’s body chemistry.

From The Skeptics Dictionary

Placebo Effect Accounts for Fifty Percent of Improvement in Depressed Patients Taking Antidepressants (1996 Press Release, American Psychological Association)

TORONTO — The debate about treating depression with drugs, psychotherapy, or a combination of both drugs and psychotherapy has raged on over the years. But a recent analysis of 39 studies of 3,252 depressed patients, presented at the American Psychological Association’s (APA) 104th annual convention, found that 50 percent of the drug effect is due to the placebo response.

In other words, a patient taking antidepressant medication with a self-reported improvement rate of 10 points, can attribute half (.5) of that improvement to the placebo effect. To determine the placebo effect of antidepressant medications, psychologist Guy Sapirstein, Ph.D., at the University of Connecticut, analyzed 39 studies of depressed patients from 1974 to 1995. The studies included patients with a primary diagnosis of depression, were randomized, and controlled for patients who received no treatment.

Studies that measured the effects of antidepressant medications such as fluoxetine (Prozac), sertaline (Zoloft) and paroxetine (Paxil) were included in the analysis. Dr. Sapirstein concluded that the pharmacologic and nonpharmacologic effects of antidepressants indicates that while only 27 percent of the response to medication is due to the medication alone (a true pharmacologic effect), 50 percent is due to the psychological impact of administering the medication (placebo effect) and 23 percent is due to other ‘nonspecific factors.’ ‘People benefitting from drugs are benefitting because they think that taking the antidepressant medicine is working,’

Dr. Sapirstein said. ‘If we take these results and say that improvement is due to what the patients think, then how people think and its effect on how they feel are more powerful than the chemical substance,’ he added. In addition, the study found that patients who either took medication or underwent psychotherapy exclusively had similar treatment outcomes. The promise of future treatment, which was controlled for by the wait-listed patients, did not affect depression levels.