A placebo, in Latin means, ‘I shall please’. It may, however, be defined as a pharmacologically inert substance (saline solution or starch tablets) that seems to produce an effect similar to what would be expected of a pharmacologically active substance.


The Placebo Effect was first mentioned at the Cornell conference of therapy in 1946. Eugene F DuBois, a New York physiologist, pointed out that, “Although placebos are scarcely mentioned in the literature, they are administered more than any other group of drugs… Although few doctors admit that they give placebos, there is a placebo ingredient in practically every prescription.” He noted that in fact, “the placebo is a potent agent and in its actions can resemble almost any drug.” At the same conference, Harry Gold added, “The placebo is a specific psychotherapeutic device with values of its own.”

Later in 1962, Kefauver-Harris Amendment of the FDA regulations led to the introduction of Placebo Controlled RCTs as the gold standard to measure the efficacy and safety of new drugs.

Since then various institutions like the National Institute of Health and the Harvard Medical School have opened up centres for placebo research.

What is the placebo effect?

Let us first consider the differences between an active drug and a placebo. They are both efficacious, their responses depend on the dose, they have their own adverse effects as well as abuse liabilities, but the effects of a placebo cannot be predictable while that of the active drug can be.

So, a placebo effect may be described as the beneficial effects that are derived from the context of clinical encounter, including the ritual of treatment and the clinician-patient relationship, as distinct from therapeutic benefits produced by the specific or characteristic pharmacological or physiological effects of medical interventions.

It is a phenomenon that a patients symptoms can be alleviated by an otherwise ineffective treatment, since the individual believes that it will work.

It is also known as – The Belief Effect, Non-specific Effect or Subject Expectancy Effect.

The various pre-requisites for a placebo to work include

  1. The alertness and attentiveness of the patient
  2. The doctor patient relationship – empathy, assurance, complete information about the beneficial effects as well as assurance regarding the adverse effects
  3. The patient – his psychological factors and prior experience
  4. The nature of the disease
  5. The drug itself – whether it is imported, costly, what is the size of the dose, whether it is an injectable formulation, what is the colour as well as the name of the drug. When used for clinical trials the placebo should look, feel, weigh, smell exactly like the active drug for its effect to occur.

Before going into the details of how a placebo works, let us look into the type of healings.

  1. Natural healing – which occurs naturally by the virtue of the endogenous products of our body. For example, wound healing.
  2. Technological healing – includes healing by the virtue of medicines, surgery and other interventions.
  3. Inter-personal healing – a healing that occurs due to the interaction between the clinician (healer) and the patient.

However, all these healing techniques have their own adverse effects. For example, natural healing may lead to autoimmune disorders, technological to iatrogenic reactions and inter-personal to ‘the nocebo effect’.

The Nocebo Effect is the opposite of the placebo effect wherein the person receiving the drug (placebo) experiences the adverse effects instead of the beneficial effects.

How does a placebo work?

The placebo works by the principle of Mind Over Medicine.

As we all know, the brain has a top-down control over all the areas of the body where the placebo works. Thus when the brain undergoes conditioning, the effects of a placebo are seen.

Let us consider an example to understand this concept.

In a study of immunosuppression caused by cyclophosphamide and a placebo, after a few doses of both the drugs, cyclophosphamide was withdrawn and only the placebo was administered. It was found that despite the absence of the active ingredient, immunosuppression was seen, hence proving the theory of brain conditioning.

The other conditions in which the placebo effect has been demonstrated include – acute pain, acupuncture analgesia, Parkinson’s disease, dementia, migraine, psychotic disorders, angina, hypertension, bronchial asthma, cough, erectile dysfunction, drug abuse, ulcerative colitis, etc.

It has been known that when in a situation where survival is of utmost importance, our brain can neglect the pain and anxiety. However, the same is not possible when the person is at rest. A question arises here that when the brain is capable of such a feat why doesn’t it work so when at rest? Why doesn’t the brain use its ‘Inner Pharmacy’ while at rest?

To begin with, we human have been condition since birth to up to individuals with authority whenever in need, like looking up to our parents. When ill, the person’s ability to think, his will and wish are impaired. In such situations, the presence of an authoritative figure, gives us the hope and expectation of relief, thereby activating the ‘Inner Pharmacy’. So, an authoritative figure is nothing but an emotional trigger of hope for relief. This phenomenon explains the placebo effect at its best.

However, one should keep in mind that the placebo acts on the illness (presentation of bodily symptoms) and not on the disease (pathological/physiological states).


Note: The above information is collected from various resources.


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