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The placebo effect is when a person’s physical or mental health appears to improve after taking a placebo or ‘dummy’ treatment. Placebo is Latin for 'I will please' and refers to a treatment that appears real, but is designed to have no therapeutic benefit. A placebo can be a sugar pill, a water or salt water (saline) injection or even a fake surgical procedure. The placebo effect is triggered by the person's belief in the benefit from the treatment and their expectation of feeling better, rather than the characteristics of the placebo. ‘Impure placebos’ are medications that have an active effect on the body, but not on the condition being treated. Placebos are often used in clinical trials to help understand the real effect of a new treatment – both positive benefits and also possible side effects. How do placebos work?It is still not known exactly how the placebo effect works. Some of the theories that attempt to explain it include:
What else helps placebos to work?Some other things that help the placebo effect to work include:
Placebos and clinical trialsPlacebos have been used in clinical trials for a long time, and are an essential part of research into new treatments. They are used to help test the effectiveness of a new health care treatment, such as a medication. For ethical (moral) reasons, people participating in clinical trials are told that they may be given a 'dummy' treatment. Usually, one group of people takes the medication while another group (the ‘control group’) takes the placebo. The placebo may be a sugar pill. In some cases, none of the participants know whether they are taking the active or inactive (placebo) substance. Sometimes, not even the researchers know (this is called a double-blind test). Comparing the results from both groups should show the effects of the medication. Around one third of people taking placebos for health complaints (including pain, headache and seasickness will experience relief from symptoms. To show that a new treatment is more effective than can just be explained by the placebo effect, the results from the people taking the new treatment are compared with the results from the people taking a placebo. The placebo effect does not imply an 'imaginary' illnessIf a person's symptoms are relieved by taking a placebo or undergoing a ‘dummy procedure’, it may seem logical to assume that their illness must have been imaginary. This is not the case. Medical research has shown that state of mind plays an important role in the development of disease. For example, stress is known to increase blood pressure, which in turn is a risk factor for heart disease. So, just as the mind can contribute to a physical disorder, it can also contribute to its cure. The argument against placebosArguments against the use of placebos, include:
The ‘nocebo’ effectThe nocebo effect describes negative outcomes (such as pain or nausea) that occur because a person was expecting to experience them. A nocebo effect can occur if a person takes a real or active medicine, and can also occur if they are given a placebo. This expectation of negative effects may be triggered when a patient is told which adverse effects they might experience before starting treatment. Open-label placebosSometimes open-label placebos are used in clinical studies. This means that people are openly and knowingly prescribed placebo medication for a condition so that doctors can’t be said to have been deceptive or dishonest. Despite being told that the medication they are taking is a placebo, the placebo effect can still occur for people using open-label placebos. It is thought that this could be due to:
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