A placebo is a fake pill that contains no medicine, but that looks exactly like the tested treatment. When studies compare several different medicines, you may not be told which treatment you are receiving. The government usually tries to carefully regulate clinical trials. The information on this page is specific to the United States, however, most developed countries offer similar regulations for clinical trials. There are several reasons why people participate in clinical trials.
Some people participate in order to get a new and otherwise unavailable treatment.
Some people participate in order to get free laboratory tests. On the other hand, there may be reasons not to participate in a clinical trial. For instance, you may be asked to stop taking other medicines that may be helping you. The treatments in the trial may have side effects, or be unsafe. Other treatments you may want to take in the future may not work as well because of drugs you took in a clinical trial.