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What Is a “Placebo Control” in a Medication Trial?

Studies of new drugs often compare the effects of an investigational drug with the effects of a placebo. If you are considering whether to take part in a drug trial, the director of the study must tell you if the study will use a placebo control. The informed consent form that you will sign if you agree to join the study must also explain any plans to use a placebo control.

The reason for using a placebo control is that the benefits from taking medications are not always due to the drug itself. These benefits are called “placebo effects.” An example is when an investigator’s enthusiasm about a new medication sometimes influences the patient’s response.

A researcher must be able to separate placebo effects from the actual effects of the drug being studied. When equal numbers of patients receive either a placebo or another standard drug that will help treat their symptoms, the researcher can better judge the actual effects of the drug being tested.

In a “double-blind, placebo-controlled” research design, the doctors and nurses working directly with patients in the study will not know which group patients are in. Only members of the research team not involved in providing day-to-day clinical care will know which patients are receiving an active treatment or a placebo. This information is shared only when there is a medical necessity to do so to protect the patient and at the end of the study.

Some scientists have questioned the use of placebo controls in clinical research. They argue that if any drug is effective in treating a given condition, then only that drug, and not a placebo, should be given as the control. Other researchers, however, believe that without a placebo control, it is harder to know whether an investigational medication is better than existing drugs. The choice depends on what is being studied, the medicine, and the illness.
If, during a study, an investigational drug seems to work very well, the researcher may stop using the placebo. In some instances, as discussed in a later section, participants may have a chance to use the investigational drug after a study is completed.

It is important that the director of a medication trial explain thoroughly any planned use of a placebo. Ask how the researcher plans to keep track of your symptoms. Also, ask if there is a possibility that your symptoms could become severe during the research project. If your symptoms worsen, at what point will the researcher decide to remove you from the study and provide standard treatment? In talking about these possibilities with the researcher, you must remember that participating in a study does not guarantee that you will receive a promising new medication. Indeed, you must consent to that fact. Also, you should remember that even if you receive an investigational drug, it may not be helpful for you. Remember you can always withdraw from a study.

What Is a “Placebo Control” in a Medication Trial?

Psych Central Staff

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APA Reference
Psych Central. (2020). What Is a “Placebo Control” in a Medication Trial?. Psych Central. Retrieved on December 2, 2020, from
Scientifically Reviewed
Last updated: 14 Jan 2020 (Originally: 17 May 2016)
Last reviewed: By a member of our scientific advisory board on 14 Jan 2020
Published on Psych All rights reserved.