Placebo Effect – What It Is and How It Works

Placebo Effect
The placebo effect is when a subject responds to a fake treatment.

The placebo effect is the phenomenon where a subject experiences an effect from an inactive substance or fake treatment, which is called a placebo. While not all people experience the placebo effect (certainly not in all situations), there are genuine therapeutic effects of placebos. Here is a look at what the placebo effect is, why it occurs, and how scientists and health professionals use it.

  • A placebo is a fake treatment, which can have genuine therapeutic value, called the placebo effect.
  • Examples of placebos include sugar pills and saline solution injections.
  • The placebo effect helps providing relief from depression, pain, and certain other conditions.
  • Overall, the placebo effect occurs because any treatment (real or a placebo) affects the brain, which responds to the stimulus and produces a physiological effect.

Placebo vs Placebo Effect

The placebo effect is a therapeutic benefit or apparent side effect from a placebo. A placebo, in turn, is a substance or treatment that has no effect. Alternatively, it is a treatment with the exact composition of inactive ingredients or the same steps as the therapy, minus the active substance or procedure.

Examples of placebos include sugar pills, consumable liquids or solids, saline injections, and fake surgeries.

The Nocebo Effect

Sometimes the placebo effect refers to any response to a fake treatment. However, other scientists refer to a therapeutic or beneficial response as the placebo effect and side effects or a negative response as the nocebo effect (negative placebo). The nocebo effect also includes withdrawal symptoms some patients experience after discontinuing a placebo treatment.

Uses of Placebos

The primary use of a placebo is in scientific research and drug testing. A researcher administers the placebo to a control group, while the experimental group receives the treatment. Assuming the placebo is identical to the treatment in every respect except the active ingredient or treatment, this type of experiment identifies the efficacy of the treatment with a high degree of confidence. Also, using a placebo makes double blind experiments possible.

However, when you compare the outcomes for an experimental group, placebo group, and a control group that receives no treatment whatsoever, then the placebo effect becomes apparent. This type of study also reveals “inactive ingredients” that aren’t actually inactive. The placebo effect does not influence the outcomes of all studies, but it is a major factor in others.

Situations Where Placebos Work

So, knowing that the placebo effect is a real phenomenon, scientists and medical professionals studied the effectiveness of placebos. In some situations, a placebo is an effective treatment, even when people know they are taking a placebo. Placebos have an effect on:

  • Asthma
  • Depression
  • Irritable bowel syndrome
  • Menopause
  • Pain
  • Sleep disorders

Studies indicate some people taking a placebo for a stimulant experience increased heart rate and blood pressure, while those taking a placebo for a depressant experience the opposite effects.

How the Placebo Effect Works

There is no single definitive mechanism for how the placebo effect works. Multiple factors likely play a role:

  • Expectation: Basically, what we believe we will experience from a treatment plays a part in the actual effect. So, if you think an injection will hurt, it probably will. Or, if you think a pill (real or placebo) helps a condition, then it likely does. Even if you know a treatment is a placebo, receiving care from a health professional aids in a positive response.
  • Conditioning: Conditioning is a learned response or association between two events. For example, in one study, rats drank a saccharin-sweetened beverage containing the immunosuppressant cyclophosphamide. After three days of conditioning, rats given the saccharin beverage minus the cyclophosphamide still displayed suppressed immune responses.
  • Genetics: Some subjects are genetically predisposed to respond to placebos. For example, in one study, people carrying a gene coding for higher levels of the neurotransmitter dopamine were more likely to experience the placebo effect than those with a gene for lower dopamine production.

Studies indicate that the brain controls a variety of responses that manifest as the placebo effect. Physiological processes subject to placebos include pain response, depression, insulin secretion, immunosuppression, symptoms of Parkinson’s disease, and serum iron levels. Brain imaging shows a placebo for pain relief activates several regions of the nervous system, including the spinal cord, amygdala, nucleus accumbens, and anterior cingulate, insular, orbitofrontal, and prefrontal cortices in the brain.


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